Objective lens drive apparatus, optical pickup device, and optical disk drive

ABSTRACT

An objective lens drive apparatus includes a stationary member, a movable portion having an objective lens, an objective-lens holding member, and driving coils, and a plurality of rod-like elastic support members each having an axial direction parallel to a third direction perpendicular to a first direction and a second direction, the support members elastically supporting the movable portion so that the movable portion is movable to the stationary member in the first direction and the second direction. The movable portion is supported by the support members on both sides of the movable portion in the third direction, the support members are arranged on different planes perpendicular to the first direction, and the movable portion is arranged to be movable in the third direction with the support members, so that the objective lens is rotatable around an axis of the second direction.

BACKGROUND OF THE INVENTION

1. Surface of The Invention

The present invention relates to an objective lens drive apparatusprovided to focus a light beam from an objective lens onto an opticaldisk as a light spot in order to perform recording/reproduction of theoptical disk, and relates to an optical pickup device incorporating theobjective lens drive apparatus, and an optical disk drive incorporatingthe optical pickup device.

2. Description of the Related Art

Conventionally, in the optical disk drive, the laser light beam, outputfrom the laser light source, is focused with the objective lens on theoptical disk as a light spot, and information is read from the opticaldisk by carrying out the opto-electric conversion of the reflected lightfrom the optical disk.

The objective lens drive apparatus, which is provided in the opticaldisk drive, drives the objective lens in the focusing direction and thetracking direction using the control signal obtained from the reflectedlight, and causes the proper light spot to be formed on the recordingsurface of the optical disk by controlling the movement of the objectivelens to follow the motion of the surface inclination of the optical diskor the eccentricity thereof.

In recent years, with the trend of high-density information recording,there is the demand to form the small light spot on the optical disk. Torealize this, it is necessary to enlarge the NA (numerical aperture) ofthe objective lens or to shorten the wavelength of laser.

However, if the NA is enlarged or the wavelength of laser is shortened,the perpendicularity of the optical axis of the objective lens to theoptical disk is shifted, and the coma aberration will easily begenerated and the quality of the light spot will deteriorate. Thiscauses the quality of recording/reproduction to deteriorate.

In order to attain high-density information recording, it is necessaryto raise the inclination accuracy between the optical disk and theobjective lens.

On the other hand, when processing mass data with the trend ofhigh-density information recording, the improvement of the speed ofrecording/reproduction is desired, and it is necessary to carry outhigh-speed rotation of the optical disk.

When the high-speed rotation of the optical disk with which the surfaceinclination or the eccentricity exists is carried out, the accelerationbecomes very large. In order to make the objective lens follow theoptical disk with sufficient accuracy, the objective lens driveapparatus that is capable of generating a large force is needed.

There are some conceivable methods to correct the inclination betweenthe optical disk and the objective lens. One of such methods is to makethe movable portion of the objective lens drive apparatus containing theoptical disk follow the inclination of the optical disk. This methodwill provide the high-speed capability to follow the rotational speed ofthe optical disk, with low cost.

For example, in the case of the method, consideration is given toincline the movable portion of the objective lens drive apparatus in theradial direction and the tangential direction. To realize this, themechanism to drive the movable portion in the four axial directions,including the focusing direction and the tracking direction, is neededfor the objective lens drive apparatus. In the objective lens driveapparatus with the multi-axial direction driving mechanism, the supportrigidity will be made small so that it may be easy to carry out movementat least in a desired driving direction. This will easily affect thedriving of the objective lens drive apparatus in the other directions.

For this reason, the cross talk generated between the driving axesbecomes large, and it will not be negligible. The main cross talk whichwill not be negligible is as follows: (1) the cross talk of the radialand tangential rotation directions which is generated by the focusingand tracking movement drive; (2) the cross talk of the tracking movementdirection which is generated by the radial movement drive; (3) the crosstalk of the tangential rotation direction which is generated by thefocusing movement drive; (4) the cross talk of the tangential movementdirection which is generated by the focusing and tracking movementdrive; and (5) the cross talk of the tangential movement direction whichis generated by the tangential rotation drive.

Japanese Laid-Open Patent Application. No. 10-275354 discloses theobjective lens drive apparatus which is configured to reduce the crosstalk. FIG. 34 shows such a conventional objective lens drive apparatus.

As shown in FIG. 34, a pair of support members 101 and 102 which havethe same structure are arranged on the plane 105 which is perpendicularto the optical axis of the objective lens 104. The ends 101 a and 102 aof the support members 101 and 102 are fixed to the side surfaces of thelens holder 106, respectively. The other ends 101 b and 102 b of thesupport members 101 and 102 are fixed to the stationary portion 107.

The support member 101 is composed of the first rod-like member 108extending from the stationary portion 107 and the second rod-like member110 extending from the lens holder 106 and being at right angles the endof the first rod-like member 108. The support member 102 is composed ofthe first rod-like member 109 extending from the lens holder 106 and thesecond rod-like member 111 extending from the lens holder 106 and beingat right angles to the end of the first rod-like member 109.

The rigidity of the objective lens 104 in the tangential rotationdirection is set such that the rigidity on the side of the ends 101 a,102 a of the support members 101, 102 is smaller than the rigidity onthe side of the other ends 101 b, 102 b of the support members 101, 102.

The drive magnets 112 and 13 are fixed to the lens holder 106. The drivecoils 114 and 115 (the focusing coil, the tracking coil, the radialdrive coil and the tangential drive coil) are provided on the stationaryportion 107. By supplying electric current to the drive coils 114 and115 respectively, the lens holder 106 including the objective lens 104is driven in the four axial directions.

With such composition of the conventional objective lens driveapparatus, it is possible to form the movable portion into a thinstructure and it is possible to provide the design in which theobjective-lens principal point, the center of inertia of the movableportion and are made to be in proximity. It is possible for theconventional objective lens drive apparatus to reduce the cross talk ofthe tangential rotation direction which is generated when driving thelens holder 106 in the focusing direction.

However, in the conventional technique of Japanese Laid-Open PatentApplication No. 10-275354, it is difficult to manage the rotationrigidity in the tangential tilt direction of the attachment section ofthe rod-like members 108,109 on the side of the lens holder 106 with thecomposition of the conventional objective lens drive apparatus of FIG.34.

Furthermore, the lens holder is supported with the rod-like members 108and 109. When it is configured by using the moving coil method, thewiring of the current to the lens holder 106 will run short. Theconventional objective lens drive apparatus of FIG. 34 is applicableonly by using the moving magnet method.

The mass of the movable portion increases when the moving magnet methodis used; since the magnet is provided on the side of the movable portionincluding the lens holder 106. The acceleration sensibility becomessmall, and it is difficult to follow the optical disk which is rotatedat high speed.

When the moving coil method is used, the density of the magnetic fluxespassing through the coil can be increased by enlarging the magnet inorder to make sensibility increase. However, when the moving magnetmethod is used, it is difficult to make sensibility increase since themass of the movable portion increases when the magnet is enlarged. It isdifficult to ensure adequate level of the acceleration which can followthe surface inclination or eccentricity of the optical disk.

With the composition of the conventional objective lens drive apparatusof Japanese Laid-Open Patent Application No. 10-275354, the movableportion is configured into a thin structure, and the magnitude of themechanical components cannot be secured enough and there is the problemthat the output acceleration is low.

Structurally, the focusing operation and the tangential tilt operationtend to influence mutually, and the occurrence of the tangential tilt iscaused by the focusing operation. There is also the problem that theservo control becomes unstable.

Japanese Patent No. 3029616 discloses another objective lens driveapparatus. FIG. 35 shows the composition of the main part of theconventional objective lens drive apparatus of Japanese Patent No.3029616.

In the composition of FIG. 35, the movable portion 122 containing theobjective lens 121 is supported by the ends of the four rod-like elasticsupport members 123-126 (two pieces on one side) which are substantiallyin parallel. By using the electromagnetic drive unit (not shown), theobjective lens 121 can be driven in the focusing direction, the trackingdirection, the radial tilt direction and the tangential tilt directionas indicated by the arrows P1 and P2 in FIG. 35.

The other ends of the rod-like elastic support members 123-126 areindependently fixed to the elastic arm 129. The elastic arm 129 isprovided so that it is rotatable around one of the axis 127 and the axis128, which are parallel to the tracking direction, in the directionsindicated by the arrows M1 and M2 in FIG. 35.

With the composition of FIG. 35, it is possible for the objective lensdrive apparatus of Japanese Patent No. 3029616 to reduce the cross talkof the tangential tilt direction generated when the movable portion 122is driven in the focusing direction.

However, in the conventional objective lens drive apparatus of FIG. 35,the composition of the elastic arm 129 on the side of the stationaryportion is complicated, and the elastic properties are not stabilized.Similar to the composition of FIG. 34, in order to deal with the tiltcompensation, the four rod-like elastic support members 123-126 areneeded, and the wiring of current supply will run short. Hence, thecomposition of FIG. 35 is applicable only by using the moving magnetmethod. There is the problem that is the same as that of the compositionof FIG. 34.

In addition, Japanese Utility Model No. 2579715 and Japanese Laid-OpenPatent Application No. 6-162540 disclose the objective lens driveapparatus in which the movable portion containing the objective lens issupported by the plurality of rod-like elastic-support members. Withsuch composition, the movability and the stability of the support areimproved.

However, in the composition of Japanese Utility Model No. 2579715 orJapanese Laid-Open Patent Application No. 6-162540, when the movableportion containing the objective lens is driven in one direction, themovement of the objective lens in the other directions becomes unstableor the movement is impossible.

Moreover, Japanese Published Utility Model Application No. 5-4096 andJapanese Laid-Open Patent Application No. 11-316963 disclose theobjective lens drive apparatus in which the end of the rod-like elasticsupport member on the side of the stationary portion is fixed to thereaf spring member.

In the composition of Japanese Published Utility Model Application No.5-4096 or Japanese Laid-Open Patent Application No. 11-316963, thedirection in which the objective lens can stably be driven is restrictedto a specific direction, and the position of the light spot on theoptical disk is changed when the objective lens is driven in thedirection.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved objectivelens drive apparatus in which the above-described problems areeliminated.

Another object of the present invention is to provide an objective lensdrive apparatus which can drive the objective lens with sufficientaccuracy at high speed.

Another object of the present invention is to provide an optical pickupdevice that is appropriate for use with an objective lens driveapparatus so that the objective lens drive apparatus can drive theobjective lens with sufficient accuracy at high speed.

Another object of the present invention is to provide an optical diskdrive that is appropriate for use with an optical pickup device andstably carries out accessing of an optical disk with the optical pickupdevice with sufficient accuracy at high speed.

The above-mentioned objects of the present invention are achieved by anobjective lens drive apparatus comprising: a stationary member; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils or magnetsgenerating a first force in a first direction parallel to an opticalaxis of the objective lens and a second force in a second directionperpendicular to the optical axis of the objective lens; and a pluralityof rod-like elastic support members each having an axial directionparallel to a third direction perpendicular to both the first directionand the second direction, the support members elastically supporting themovable portion so that the movable portion is movable to the stationarymember in the first direction and the second direction, wherein themovable portion is supported by the support members on both sides of themovable portion in the third direction, the support members are arrangedon different planes perpendicular to the first direction, and themovable portion is arranged to be movable in the third direction withthe support members, so that the objective lens is rotatable around anaxis of the second direction.

The above-mentioned objects of the present invention are achieved by anobjective lens drive apparatus comprising: a stationary member; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils or magnets; and aplurality of rod-like elastic support members provided between thestationary member and the movable portion, each support member having anaxial direction that is parallel to a third direction perpendicular toboth a first direction and a second direction, the support memberselastically supporting the movable portion to be movable to thestationary member, wherein the movable portion is supported by thesupport members on both sides of the movable portion, and the supportmembers are arranged on a single plane perpendicular to the firstdirection and in the third direction symmetrically with respect to anoptical axis of the objective lens.

The above-mentioned objects of the present invention are achieved by anobjective lens drive apparatus comprising: a stationary member; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils or magnets; and aplurality of rod-like elastic support members provided between thestationary member and the movable portion, each support member having anaxial direction that is parallel to a third direction perpendicular toboth a first direction and a second direction, the support members beingarranged in the first direction apart from each other and elasticallysupporting the movable portion to be movable to the stationary member atleast in a tilt direction of the third direction, wherein the movableportion is supported by the support members on both sides of the movableportion, and the support members are arranged on a single planeperpendicular to the first direction and in the third directionsymmetrically with respect to an optical axis of the objective lens, theend on the side of the stationary member which supported the movableportion by the support members from both sides in the third direction,and is estranged in the first direction in the support member, it isfixed to the part from which the radius of gyration on the elastic boardwhich the width of face of the focusing direction is formed narrowlypartially, respectively, and rotates the shaft of the tracking directionas a center differs, the objective lens drive apparatus is configured sothat the elastic board is rotatable corresponding to tangential tiltoperation of the movable portion.

The above-mentioned objects of the present invention are achieved by anoptical pickup device comprising: an objective lens drive apparatus; alaser light source outputting a laser light beam to an optical disk; alight-receiving optical unit receiving a reflected light beam from theoptical disk; and an objective-lens control unit outputting a controlsignal to the objective lens drive apparatus based on the reflectedlight beam received by the light-receiving optical unit, the objectivelens drive apparatus comprising: a stationary member; a movable portionhaving an objective lens, an objective-lens holding member holding theobjective lens, and driving coils or magnets generating a first force ina first direction parallel to an optical axis of the objective lens anda second force in a second direction perpendicular to the optical axisof the objective lens; and a plurality of rod-like elastic supportmembers each having an axial direction parallel to a third directionperpendicular to both the first direction and the second direction, thesupport members elastically supporting the movable portion so that themovable portion is movable to the stationary member in the firstdirection and the second direction, wherein the movable portion issupported by the support members on both sides of the movable portion inthe third direction, the support members are arranged on differentplanes perpendicular to the first direction, and the movable portion isarranged to be movable in the third direction with the support members,so that the objective lens is rotatable around an axis of the seconddirection.

The above-mentioned objects of the present invention are achieved by anoptical disk drive in which an optical pickup device, a rotation driveunit controlling rotation of an optical disk, and a pickup drive unitmoving the optical pickup device in a radial direction of the opticaldisk, the optical pickup device comprising: an objective lens driveapparatus; a laser light source outputting a laser light beam to theoptical disk; a light-receiving optical unit receiving a reflected lightbeam from the optical disk; and an objective-lens control unitoutputting a control signal to the objective lens drive apparatus basedon the reflected light beam received by the light-receiving opticalunit, the objective lens drive apparatus comprising: a stationarymember; a movable portion having an objective lens, an objective-lensholding member holding the objective lens, and driving coils or magnetsgenerating a first force in a first direction parallel to an opticalaxis of the objective lens and a second force in a second directionperpendicular to the optical axis of the objective lens; and a pluralityof rod-like elastic support members each having an axial directionparallel to a third direction perpendicular to both the first directionand the second direction, the support members elastically supporting themovable portion so that the movable portion is movable to the stationarymember in the first direction and the second direction, wherein themovable portion is supported by the support members on both sides of themovable portion in the third direction, the support members are arrangedon different planes perpendicular to the first direction, and themovable portion is arranged to be movable in the third direction withthe support members, so that the objective lens is rotatable around anaxis of the second direction.

According to the objective lens drive apparatus of the presentinvention, it is possible to correct the inclination error of theoptical disk and the objective lens. By making it possible to generatethe driving force which can follow the optical disk under high-speedrotation to carry out the independent drive at each shaft orientations,the movability of the tangential tilt direction can be made good, andthe sensibility can be made small.

The optical disk drive of the present invention can perform stablecontrol and it sets to the objective lens drive apparatus dealing withinclination compensation. The cross talk between the drive shafts whichare easy to pose the problem can be reduced. Specifically, it ispossible to reduce the cross talk including the cross talk of thetangential rotation direction generated by focusing translation drive,the cross talk of the tangential movement direction generated byfocusing or tracking translation drive, and the cross talk of thetangential movement direction generated by the tangential rotationdrive.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

FIG. 1 is a perspective FIG. of the objective lens drive apparatus ofone preferred embodiment of the present invention.

FIG. 2 is a front FIG. of the objective lens drive apparatus of FIG. 1.

FIG. 3 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 4 is a front FIG. of the objective lens drive apparatus of FIG. 3.

FIG. 5 is a diagram showing the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 6 is a diagram showing the main portion of the objective lens driveapparatus of another preferred embodiment of the present invention.

FIG. 7 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 8 is a front FIG. of the objective lens drive apparatus of FIG. 7.

FIG. 9 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 10 is a front FIG. of the objective lens drive apparatus of FIG. 9.

FIG. 11 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 12 is a diagram showing the electromagnetic drive unit in theobjective lens drive apparatus of FIG. 11.

FIG. 13 is a diagram showing the objective lens holding member in theobjective lens drive apparatus of FIG. 11.

FIG. 14 is a diagram showing the rod-like flat spring in the objectivelens drive apparatus of FIG. 1.

FIG. 15 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 16 is a diagram showing the objective lens holding member in theobjective lens drive apparatus of FIG. 15.

FIG. 17 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 18 is a diagram showing the main portion of the objective lensholding member in the objective lens drive apparatus of FIG. 17.

FIG. 19 is a diagram showing the structure of the wire spring and theelastic board in the objective lens drive apparatus of FIG. 17.

FIG. 20 is a diagram showing the structure of the printed circuit boardin the objective lens drive apparatus of FIG. 17.

FIG. 21 is a diagram showing the main portion of the objective lensdrive apparatus of another preferred embodiment of the presentinvention.

FIG. 22 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 23 is a diagram showing the electromagnetic drive unit in theobjective lens drive apparatus of FIG. 22.

FIG. 24 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 25A and FIG. 25B are diagrams for explaining the arrangement of thewire springs in the objective lens drive apparatus of FIG. 24.

FIG. 26 is a perspective FIG. of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 27 is a diagram for explaining the arrangement of the wire springsin the objective lens drive apparatus of FIG. 26.

FIG. 28 is a diagram for explaining the arrangement of the wire springsin the objective lens drive apparatus of FIG. 26.

FIG. 29 is a diagram showing the objective lens holding member in theobjective lens drive apparatus of another preferred embodiment of thepresent invention.

FIG. 30 is a diagram showing the objective lens holding member in theobjective lens drive apparatus of another preferred embodiment of thepresent invention.

FIG. 31 is a diagram showing an optical pickup device in which theobjective lens drive apparatus of one embodiment of the presentinvention is provided.

FIG. 32 is a diagram showing an optical disk drive in which the opticalpickup device of FIG. 31 is provided.

FIG. 33 is a front view of the optical disk drive of FIG. 32.

FIG. 34 is a diagram showing a conventional objective lens driveapparatus.

FIG. 35 is a diagram showing another conventional objective lens driveapparatus.

FIG. 36 is a perspective view of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 37 is a top view of the objective lens drive apparatus of FIG. 36.

FIG. 38 is a side view of the objective lens drive apparatus of FIG. 36.

FIG. 39 is an exploded view of the coils, yokes and magnets in theobjective lens drive apparatus of FIG. 36.

FIG. 40A, FIG. 40B, FIG. 40C and FIG. 40D are diagrams for explainingthe tilt compensation operation in the objective lens drive apparatus ofFIG. 36.

FIG. 41 is a perspective view of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 42A, FIG. 42B and FIG. 42C are diagrams for explaining the tiltcompensation operation in the objective lens drive apparatus of FIG. 41.

FIG. 43A and FIG. 43B are diagrams for explaining the cancellation ofthe cross-action in the direction of the jitter.

FIG. 44 is a diagram showing variation of the objective lens driveapparatus of FIG. 41.

FIG. 45 is a perspective view of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

FIG. 46A, FIG. 46B, FIG. 46C and FIG. 46D are diagrams for explainingthe tilt compensation operation in the objective lens drive apparatus ofFIG. 45.

FIG. 47 is a diagram showing variation of the tilt compensation driveunit.

FIG. 48 is a diagram showing an optical pickup device in which theobjective lens drive apparatus of one embodiment of the presentinvention is provided.

FIG. 49 is a diagram showing an optical disk drive in which the opticalpickup device of FIG. 48 is provided.

FIG. 50 is a front view of the optical disk drive of FIG. 49.

FIG. 51 is a block diagram of an optical disk drive to which theobjective lens drive apparatus of one embodiment of the presentinvention is applied.

FIG. 52 is a block diagram of the reproduced signal processing circuitin the optical disk drive of FIG. 51.

FIG. 53 is a diagram showing the optical pickup device in the opticaldisk drive of FIG. 51.

FIG. 54 is a diagram showing the outgoing light beam optical system inthe optical pickup device of FIG. 53.

FIG. 55 is a diagram showing the focusing system in the optical pickupdevice of FIG. 53.

FIG. 56A and FIG. 56B are diagrams showing the focusing system in theoptical pickup device of FIG. 53.

FIG. 57A and FIG. 57B are diagrams showing the first and second magnetportions in the optical pickup device of FIG. 53.

FIG. 58A, FIG. 58B, FIG. 58C and FIG. 58D are diagrams showing therespective coils for driving the lens holder.

FIG. 59A and FIG. 59B are diagrams for explaining the relationship ofthe magnets and the coils to drive the lens holder.

FIG. 60A, FIG. 60B, FIG. 60D, FIG. 60E and FIG. 60F are diagrams forexplaining the lens holder driving operation.

FIG. 61A, FIG. 61B and FIG. 61C are diagrams for explaining the radialand tangential tilt compensation.

FIG. 62A, FIG. 62B, FIG. 62C and FIG. 62D are diagrams showing variationof the radial tilt coils.

FIG. 63A and FIG. 63B are diagrams for explaining the positionalrelationship of the magnets and the coils in the arrangement of FIG. 62Athrough FIG. 62D.

FIG. 64A and FIG. 64B are diagrams for explaining the operations of theradial tilt coils of FIG. 62A through FIG. 62D.

FIG. 65A, FIG. 65B, FIG. 65C and FIG. 65D are diagrams showing anothervariation of the radial tilt coils.

FIG. 66A and FIG. 66B are diagrams for explaining the positionalrelationship of the magnets and the coils in the arrangement of FIG. 65Athrough FIG. 65D.

FIG. 67A and FIG. 67B are diagrams for explaining the operations of theradial tilt coils of FIG. 65A through FIG. 65D.

FIG. 68A and FIG. 68B are diagrams showing variation of the arrangementof the magnets.

FIG. 69A, FIG. 69B, FIG. 69C and FIG. 69D are diagrams for explainingthe arrangement of the coils corresponding to the arrangement of themagnets of FIG. 68A and FIG. 68B.

FIG. 70A and FIG. 70B are diagrams for explaining the positionalrelationship of the magnets and the coils in the arrangement of FIG. 69Athrough FIG. 69D.

FIG. 71A and FIG. 71B are diagrams for explaining the operations of theradial tilt coils of FIG. 69A through FIG. 69D.

FIG. 72A and FIG. 72B are diagrams showing another variation of thearrangement of the magnets.

FIG. 73A and FIG. 73B are diagrams for explaining the positionalrelationship of the magnets and the coils in the arrangement of FIG. 72Aand FIG. 72B.

FIG. 74A and FIG. 74B are diagrams for explaining the operations of theradial tilt coils of FIG. 73A and FIG. 73B.

FIG. 75A and FIG. 75B are diagrams showing another variation of thearrangement of the magnets.

FIG. 76A and FIG. 76B are diagrams for explaining the positionalrelationship of the magnets and the coils in the arrangement of FIG. 75Aand FIG. 75B.

FIG. 77A and FIG. 77B are diagrams for explaining the operations of theradial tilt coils of FIG. 76A and FIG. 76B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A description will now be provided of the preferred embodiments of thepresent invention with reference to the accompanying drawings.

FIG. 1 shows the objective lens drive apparatus of one preferredembodiment of the present invention. FIG. 2 is a front FIG. of theobjective lens drive apparatus of FIG. 1.

In FIG. 1 and FIG. 2, reference numeral 1 indicates the objective lens,and reference numeral 2 indicates the objective-lens holding memberwhich forms a movable portion in which the objective lens 1 is mountedat the central upper part of the movable portion. The focusing coils 3(only two pieces on one side are shown) are held on the objective-lensholding member 2.

In the objective lens drive apparatus of FIG. 1, the tracking coils 4 aand 4 b are held on the objective-lens holding member 2. The plural wiresprings 5 a-5 d form the rod-like elastic supporting member which holdsthe objective-lens holding member. The wire springs 5 a-5 d serve as themovable-portion supporting member which supports the movable portion. Inthe present embodiment, the eight wire springs 5 a-5 d are provided, andthe four of them are provided on one side of the tangential direction,and the remaining four are provided on the other side (but they are notshown).

The objective lens drive apparatus of FIG. 1 includes the stationarymembers 6, the base member 7, the magnets 8, the yoke portions 9 and theelastic boards 10. The magnets 8 are arranged on the inside walls of thestationary members 6 so that they are opposed to the focusing coils 3and the tracking coils 4 a and 4 b. Each of the elastic boards 10 isformed by a flexible circuit board.

In FIG. 1 and FIG. 2, the objective-lens holding member 2 which holdsthe objective lens 1 is elastically supported by the eight wire springs5 a-5 d at the support projections 2 a and 2 b which project from theholding member 2 in the opposing directions. The axial directions of thewire springs 5 a-5 d are parallel to the tangential direction which isperpendicular to both the focusing direction and the tracking direction.The four of the wire springs 5 a-5 d are arranged on one side of thetangential direction of the optical disk which is arecording/reproduction medium, and the remaining four are arranged onthe opposite side of the tangential direction. The eight wire springs intotal are arranged in parallel and at the symmetrical positions on thetwo surfaces that are perpendicular to the focusing direction.

The four focusing coils 3 and the two tracking coils 4 a and 4 b areattached to the corners of the objective-lens holding member 2. Theobjective-lens holding member 2 with the focusing coils 3 and thetracking coils 4 a and 4 b attached serves as the movable portion to thestationary members 6.

The wire springs 5 a-5 d are made of a conductive substance, and theends of the wire springs 5 a-5 d are secured to the elastic board 10 bysoldering. The wire springs 5 a-5 d serve as the current supply memberswhich respectively supply the current to the drive coils 3, 4 a, 4 bfrom the ends of the wire springs 5 a-5 d on the side of the stationarymembers 6.

The elastic boards 10 are formed by flexible circuit boards. Theflexible circuit boards 10 are provided with the wiring that is used tosupply the current to the drive coils (the focusing coil 3 and thetracking coils 4 a and 4 b) through the wire springs 5 a-5 d.

As shown in FIG. 1, the focusing direction is parallel to the directionof the optic axis of the objective lens 1 and corresponds to the firstdirection in the claims. The tracking direction is perpendicular to thedirection of the optical axis of the objective lens 1 and corresponds tothe second direction in the claims. The tangential direction isperpendicular to both the focusing direction and the tracking directionand parallel to the axial directions of the wire springs 5 a-5 d, andcorresponds to the third direction in the claims.

The portions of the elastic boards 10 to which the wire spring ends aresecured are arranged so that the wire springs 5 a-5 d are displaceablein the axial directions of the wire springs (which are parallel to thetangential direction). The elastic boards 10 are attached to thestationary members 6 which are fixed to the base member 7.

The base member 7 is the magnetic substance and forms the yoke section 9by bending the part. The magnetic circuit is formed so that the magneticflux may pierce in each drive coil with the magnet 8 fixed to this yokesection 9.

It is possible to drive the movable portion to the focusing direction,the radial tilt direction, and the tangential direction by attachingfour focusing coils 3 in the four corners of the objective-lens holdingmember 2, and adjusting the current passed in each focusing coil 3.

Moreover, by passing the current in the tracking coils 4 a and 4 b, itis possible to drive the movable portion containing the objective-lensholding member 2 to the tracking direction, the face deflection in theoptical disk which rotates at high speed, eccentricity, the curvature,etc. can be followed, and it is possible to form the good light spot inthe optical disk side.

When it is going to drive the objective lens 1 only to the focusingdirection, by making four focusing coils 3 generate equivalent drivingforce, the driving force to the focusing direction occurs at the centerin the objective-lens holding member 2.

On the other hand, since the part which differs from the driving forcegenerating part with the wire springs 5 a-5 d to the stationary members6 is supported, the moment will generate the objective-lens holdingmember 2 by the difference in the position of the driving point and thesupporting point.

However, since the objective-lens holding member 2 in the presentembodiment is the symmetrical configuration as a center, and are theboth sides of the tangential direction and the optical axis of theobjective lens 1 is supported in the equivalent distance, the momentwhich occurred on both sides of the tangential direction will becanceled mutually.

Therefore, even if it makes small rotation rigidity (or rigidity in thetangential movement direction) in the tangential direction in order tocarry out tilt compensation since the moment will not occur in theobjective-lens holding member 2 as a whole, it does not rotate to thetangential direction.

In the present embodiment, the cross talk of the tangential directiongenerated by focusing translation drive can be reduced.

Moreover, with the composition which makes rotation rigidity in thetangential direction small, since it is what makes small rigidity in theshaft orientations of the wire spring, it becomes easy to generate theoptical-axis gap in the tangential movement direction.

Moreover, since the wire spring is bent by the usual wire support methodwhen the objective-lens holding member is moved to the focusingdirection or the tracking direction, it will become short to shaftorientations and the objective lens will move to the tangentialdirection.

However, in the present embodiment, since the objective-lens holdingmember 2 is supported on tangential-direction both sides and rigidity(spring modulus of each part) is also set up equally, it is possible forthe force of shaft orientations (tangential direction) when theobjective-lens holding member 2 moves to the focusing direction or thetracking direction to balance, and to suppress movement to thetangential direction of the objective lens 1.

In the present embodiment, the cross talk of the tangential movementdirection generated by focusing translation drive can be reduced.

FIG. 3 is a perspective view of the objective lens drive apparatus ofanother preferred embodiment of the present invention. FIG. 4 is a frontview of the objective lens drive apparatus of FIG. 3.

In FIG. 3 and FIG. 4, the elements which are essentially the same ascorresponding elements in FIG. 1 are designated by the same referencenumerals, and a description thereof will be omitted.

In the objective lens drive apparatus to which tilt compensation isperformed, the cross talk of the tangential movement direction occursalso by carrying out the tangential-tilt drive.

This will be generated when the center of rotation in the tangentialdirection is distant from the principal point of the objective lens.

In the preferred embodiment of FIG. 3, in order to carry out the centerof rotation in the tangential direction near the principal point of theobjective lens 1, the previous embodiment is modified and the followingcomposition is adopted.

In FIG. 3 and FIG. 4, the wire springs 5 a-5 d are opposed to thefocusing direction (the direction of the optical axis of the objectivelens 1) on two perpendicular virtual planes.

The elastic board 1 to which the edge of the wire springs 5 a and 5 barranged considering the tangential direction as a lengthening joint,constitutes one of the two virtual surfaces in which the wire springs 5a-5 d are arranged so that the principal point M of the objective lens 1may be included, and are arranged in the virtual plane is fixed.

It is set up so that rigidity of the tangential direction may beenlarged (or it sets up so that it may become the rigid body).

It is made to specifically regulate the motion of the elastic board 10by the stationary members 6 like the section shown in FIG. 3.

Moreover, it sets up so that rigidity of the tangential direction of theelastic board to which the wire springs 5 c and 5 d arranged to thevirtual side of another side are fixed may be made small.

When the driving force of the tangential direction occurs in theobjective-lens holding member 2, it is possible to carry out the tilt atthe center of the principal point M of the objective lens 1.

In the present embodiment, the cross talk of the tangential movementdirection generated by the tangential rotation drive can be reduced.

The direction made to extend to near the optical axis of the objectivelens 1 as much as possible tends to carry out the tilt drive of thefixed end on the side of the wire springs 5 a-5 d at the projections 2 aand 2 b of the objective-lens holding member 2.

It is also possible to suppress the occurrence of the cross talk of thetangential tilt generated by the focusing movement and the tangentialmovement direction by supporting the both sides of the tangentialdirection symmetrically to the objective-lens holding member 2.

In the above-mentioned embodiments, it is possible to support therotation of the objective-lens holding member 2 by fixing the fixed-endsection on the side of the stationary member 6 in the wire springs 5 a-5d to the elastic boards 10 which can be displaced to the tangentialdirection.

In order to give elasticity to the tangential movement direction, it ispossible to form the wire spring as follows.

FIG. 5 shows the main part of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

In the present embodiment, the end on the side of the stationary members6 in the wire springs 5 a-5 d in the preferred embodiment 1 is fixed tothe stationary members 6 which does not move to the tangential axisdirection.

As the wire springs 5′a-5′d, the flat spring formed of not the roundedwire but etching processing or fine-punching processing of the laminasheet metal is used, and it is the bending bent portion 1 about themiddle of wire springs 5′a-5′d.

The objective-lens holding member 2 is supported in elasticity to thetangential axis direction by forming 1 and forming the part which iseasy to bend in the tangential direction.

The other composition of the present embodiment is the same as thecomposition of the previous embodiment.

Since it is unnecessary to attach to the elastic boards 10 by giving theelasticity of the tangential direction to the wire springs 5′a-5′d whichinclude the flat spring, the attaching operation can be made easy.

FIG. 6 shows the main part of the objective lens drive apparatus ofanother preferred embodiment of the present invention.

The end on the side of the stationary members 6 in the wire springs 5a-5 d is fixed to the stationary members 6 which does not move to thetangential direction. Moreover, the end on the side of theobjective-lens holding member 2 in the wire springs 5 a-5 d.

It attaches in the lobe 12 which is easy to bend in the tangentialdirection (the direction of the arrow head), and is formed in theobjective-lens holding member 2 at it, or attaches in the flexiblemember (not shown) which is fixed to the objective-lens holding member2, and can bend in the tangential direction.

It becomes possible like the preferred embodiment 1 and the preferredembodiment 2 to support the objective-lens holding member 2 inelasticity to the tangential axis direction.

In addition, the composition of others in the preferred embodiment 4 isthe same as the composition of the previous embodiment 1.

FIG. 7 shows the objective lens drive apparatus of another preferredembodiment of the present invention. FIG. 8 is a front FIG. of theobjective lens drive apparatus of FIG. 7.

In the present embodiment, a thin structure of the objective lens driveapparatus is attained by arranging the objective lens drive apparatusand the optical system in the same surface in the height direction.

In the present embodiment, the support composition of the objective-lensholding member 2 can adopt all of the composition of the preferredembodiments.

In the objective lens drive apparatus in which inclination compensationis possible, the objective-lens holding member 2 will be thinly formedin the focusing direction in order to locate the drive center and thecenter of inertia (center of gravity) near the principal point of theobjective lens 1, it is difficult to secure the driving force.

Although the driving force of the objective lens drive apparatus isgenerated by constituting so that the drive coil passes through themagnetic flux, when driving the two shafts of the focusing direction andthe tracking direction at least, the direction of the magnetic fluxarranges the magnet 8 in many cases so that the direction perpendicularto the tangential direction, may be generated.

For this reason, it is more efficient to arrange the front face (largesurface) of the magnet 8 to the virtual flat surface and parallel whichpass along both the shafts of the focusing direction and the trackingdirection.

Moreover, although the layout which bends the laser light beam L whichcarries out incidence to the objective lens 1 using the starting mirror13 which deflects the laser light beam L upwards in the lower part (theoptical disk installation side and opposite side) of the objective lens1 the 90 degrees is common in order to make equipment form thinly.

With the composition with which the thin structure is important and themagnetic circuit is arranged at the tangential-direction both sides inthe objective-lens holding member 2, in order that the magnetic-circuitpart may interrupt the laser light beam L, it is not suitable.

Then, it is made composition which does not arrange the components tothe one side of the objective lens 1, and from the one side, incidenceof the laser light beam L can be carried out, and the thin structure canbe attained by arranging the objective lens drive apparatus and theoptical system to the same surface.

However, in order for the high order resonance by the movable portion,such as the objective lens 1 and the objective-lens holding member 2,carrying out the elastic deformation in the drive high frequency rangeby the objective lens drive apparatus of composition of supporting theobjective lens 1 by the one side in this way to get worse and to degradethe servo property remarkably, it becomes difficult to make it followwith high precision at high speed.

That is, the direction which arranges the objective lens 1 at the centerof the objective-lens holding member 2, and arranges the magneticcircuit on both sides tends to secure the high order resonance property.

However, if this configuration is made thin, the superficial content ofthe magnetic circuit becomes small, and since the space of the drivecoil arranged decreases, the problem will arise that it is hard toacquire large driving force.

Only the focusing coil 3 does not need to make the center of gravity ofthe objective-lens holding member 2 in agreement with the focusingdirection in the drive coil.

Therefore, the magnetic circuit is formed in the focusing direction fora long time, the drive coil 15 as the tracking drive coil, the radialdrive coil, and a tangential drive coil is arranged to the optical diskinstallation side, and it is the focusing coil in the optical diskinstallation side and the opposite side.

By arranging 16, it is the focusing coil from the objective-lens holdingmember 2.

Although 16 projects in the opposite side the optical disk installationside of the focusing direction, from the radial direction in theobjective-lens holding member 2, space will be vacant.

The optics portion of the objective lens drive apparatus can be arrangedin the same surface in the focusing direction by turning up the 90degrees to the optical disk installation side by the mirror 13 bycarrying out incidence of the laser light beam L from the radialdirection in this part, and rising in the part pinched by the lower partof the focusing coil 16 or the magnetic circuit. It is possible for thepresent embodiment to form the whole equipment thinly.

FIG. 9 shows the objective lens drive apparatus of another preferredembodiment of the present invention. FIG. 10 is a front view of theobjective lens drive apparatus of FIG. 9.

In the present embodiment, the modification of the previous preferredembodiment is the objective-lens holding member.

By taking a large width of the spacing of the support projections 2 aand 2 b near the center of the objective-lens holding member 2 in thetangential direction for the wire springs 5 a-5 d, it becomes possibleto make the laser light beam L from the tracking direction to beincident to the spacing. By piling up a part of the optical system andthe objective lens drive apparatus in the height direction, it ispossible to make the height of the whole equipment small.

In the present embodiment, the configuration of the moving coil methodis adopted. However, the present invention is also applicable even if itis the moving magnet method which installs the magnet in theobjective-lens holding member as an electromagnetic drive unit.

FIG. 11 shows the objective lens drive apparatus of another preferredembodiment of the present invention. FIG. 12 shows the main part of theelectromagnetic drive unit in the preferred embodiment of FIG. 11. FIG.13 shows the objective-lens holding-member in the preferred embodimentof FIG. 11.

In the present embodiment, the objective-lens holding member 2 holdingthe objective lens 1 is supported in elasticity by the rod-like flatspring 17 which is the rod-like elastic-support object which makes thetangential direction the lengthening joint.

The bent portion 17 a is formed in part, and the rod-like flat spring 17is allotted on the one flat surface perpendicular to the focusingdirection, and it totals it four on both sides of the tangentialdirection and the radial direction focusing on the optical axis of theobjective lens 1. Eight are arranged in parallel.

In FIG. 12 and FIG. 13, the aspect of the tangential direction of theobjective-lens holding member 2 is equipped with four types of drivecoils including the first focusing coil 3 a, the second focusing coil 3b, the tracking coil 4 between the focusing coils 3 a, 3 b, and theradial tilt coils 18 a and 18 b connected to the focusing coils 3 a and3 b, and the movable portion is thus constituted.

The base member 7 is made of the magnetic substance and forms the yokesection 9 by bending the part.

The driving magnet 8 fixed to the yoke section 9 is arranged at the bothsides of the tangential direction in the objective-lens holding member2, and it is arranged so that the magnetic flux may pass through boththe focusings coils 3 a and 3 b, the tracking coil 4, and the radialtilt coils 18 a and 18 b, and the magnetic circuit is thus formed.

The divisional magnetization of the magnet 8 is carried out by themagnetization boundary line a of the focusing direction in the center ofthe tracking direction. The division magnetization of the both sides ofthe magnetization boundary line a is further carried out by themagnetization boundary line b of the focusing direction perpendicular tothe end surface on the side of the optical disk installation in themagnet 8, and the magnetization boundary line c perpendicular to theaspect of the tracking direction in the magnet 8 in the L-shapedformation.

The first focusing coil 3 a and second focusing coil 3 b are woundaround the axis of the tangential direction, and they are arranged atthe both sides in the tracking direction of the magnetization boundaryline a of the magnet 8.

The part to which the current flows to the two tracking directions ofthe focusing coils 3 a and 3 b is arranged at the both sides in thefocusing direction of the magnetization boundary line c, respectively,and the part to which the current flows to the focusing direction isarranged ranging over the magnetization boundary line b.

The tangential direction is wound around the tracking coil 4 as a shaft,the magnet 8 is countered, and the part to which the current flows tothe tracking direction is constituted ranging over the magnetizationboundary line a.

The radial tilt coils 18 a and 18 b are wound around the axis of thetangential direction, and they are arranged at the both sides of themagnetization boundary line a.

It is constituted so that the part to which the current flows to thetracking direction on the side of optical disk installation ranges overthe magnetization boundary line b of the magnet 8, while the part towhich the current flows to the focusing direction of the side far fromthe magnetization boundary line a ranges over the magnetization boundaryline c of the magnet 8.

The movable portion can be driven to the focusing direction by passingthe equivalent current to the first focusing coil 3 a and the secondfocusing coil 3 b.

Moreover, driving to the tangential tilt direction is possible by givingthe difference to the current passing through the first focal coil 3 aand the current passing through the second focusing coil 3 b.

Moreover, it can drive in each direction by passing the current throughthe tracking coil 4 and the radial tilt coils 18 a and 18 b.

The eight rod-like flat springs 17 are manufactured by etching orprecision sheet metal work, are setting thickness to about 50micrometers, and as shown in the plan showing in FIG. 14, after theyreally cast the one plate-like member 19 by this example to theobjective-lens holding member 2 and the stationary members 6, they canform it by excising the unnecessary part by it.

By doing in this way, the positioning accuracy to the span between eachrod-like flat spring 17 or the objective-lens holding member 2, and thestationary members 6 improves, and it becomes possible further to alsomake small struggling between the individuals of the rod-like flatspring 17.

While the movability improves by crookedness section 17 a prepared in apart of rod-like flat spring 17, the deformation of the lengtheningjoint in the rod-like flat spring 17 at the time of operation can beabsorbed, and struggling in primary resonance frequency or displacementsensibility can be reduced.

FIG. 15 is a perspective view of the objective lens drive apparatus ofanother preferred embodiment of the present invention, and FIG. 16 is adiagram showing the objective-lens holding member in the preferredembodiment of FIG. 15. In FIG. 15 and FIG. 16, the elements which areessentially the same as corresponding elements in the previousembodiment are designated by the same reference numerals, and adescription thereof will be omitted.

In the present embodiment, apart from the previous embodiment, it isarranged so that it may become small (thinly) on the whole in thefocusing direction, and the rod-like flat spring 17 is arranged on theflat surface near the principal-point A of the objective lens 1.

Therefore, the support center will be arranged near the principal-pointA of the objective lens 1.

When the center of gravity of the movable portion is given the radialtilt driving force or tangential-tilt driving force to the movableportion by arranging it near the principal point A of the objective lens1, the rotation operation is performed on the center of the principalpoint A of the objective lens 1.

Since the light spot on the optical disk focused with the objective lens1 is not fluctuated to the tracking direction or the tangentialdirection, stable servo operation is attained.

FIG. 17 shows the objective lens drive apparatus of another preferredembodiment of the present invention. FIG. 18 is an enlarged view of theprinted circuit board part of the objective-lens holding member in theembodiment of FIG. 17.

The objective-lens holding member 2 holding the objective lens 1 issupported in elasticity in the preferred embodiment 9 with the wiresprings 5 which makes the tangential direction the lengthening joint.

Four a total of eight are arranged in parallel by the both sides of thetangential direction and the radial direction focusing on the opticalaxis of the objective lens 1 on one flat surface with the wire springs 5perpendicular to the focusing direction.

After arranging two wire springs 5 with the tangential direction foreach of the both sides respectively and carrying out solder fixation ofthe one wire spring from the first at the movable portion and thestationary portion of the objective lens drive apparatus, it is possibleby excising the unnecessary section to raise the positioning accuracy tothe span or the objective-lens holding member 2, and the stationarymembers 6.

It is made for the edge of the tangential direction in the land of theprinted circuit board 20 by which solder fixation is carried out and thewire spring 5 which adjoins further is being fixed to the land of theprinted circuit board 20 arranged at right angles to the focusingdirection in the radial-direction both sides of the objective-lensholding member 2 to be located in the same ridgeline R, as the fixed-endsection on the side of the movable portion in eight wire springs 5 is asshown in FIG. 18.

Since the effective length in the wire spring 5 is decided in the board10 of the stationary members 6 and the ridgeline R which fix the otheredges of 5, struggling in the die length of the wire spring 5 can besuppressed to the minimum.

The fixed-end section on the side of the stationary members 6 of thewire spring 5 may be made to carry out solder fixation at the elasticboard 21 which has flexibility in the shaft orientations of the wirespring 5, and is moved slightly to them, as shown in FIG. 19. It ispossible to improve the movability by this composition.

Moreover, the printed circuit board 20 of the objective-lens holdingmember 2 is arranged in the objective lens 1 on both sides of the centerof gravity G of the movable portion at the opposite side (lower partside), as shown in FIG. 20.

Usually, since the objective lens 1 with large mass is arranged at theoptical disk installation side, the center of gravity G of the movableportion tends to approach the optical disk installation side.

Although it is necessary to attach the weight for the balancers in thelower part of the movable portion in order to make this center ofgravity G in agreement with the support center and the drive center, inthe present embodiment, by making the printed circuit board 20 serve adouble purpose as a balancer, components mark are reduced and it makesit possible to reduce the weight of the movable portion.

The stationary member in the rod-like elastic member (the wire springs5, 5 a-5 d, and the rod-like flat spring 17) if it is in the objectivelens drive apparatus of composition of supporting the movable portion bythe spring member, in order to make the primary resonance detected fromthe support system and the moving-part mass property usually decrease.

The viscoelasticity ingredient is prepared in the end on the side of sixin many cases.

Then, as shown in the perspective diagram showing the principal part ofthe objective lens drive apparatus for explaining the preferredembodiment of FIG. 21, in order to make resonance of the tangential tiltdirection fully decrease, the deformation of the wire spring 5 on theside of the movable portion has formed the viscoelasticity ingredient 22in the large part, and the large damping effect is made to be acquiredin the preferred embodiment.

In addition, if the viscoelasticity material 22 is formed also in theedge of the wire spring 5 on the side of the stationary members 6, thedamping effect will increase further.

FIG. 22 shows the objective lens drive apparatus of another preferredembodiment of the of the present invention, and FIG. 23 shows theelectromagnetic drive unit in the objective lens drive apparatus of FIG.22.

As shown, the movable portion includes the objective-lens holding member2 holding the objective lens 1 and the drive coil is supported inelasticity in the present embodiment with the wire spring 5 which makesthe tangential direction the lengthening joint to the stationaryportion.

The wire spring 5 is estranged to two in the focusing direction, and atotal of eight are installed four symmetrically with each of thetangential direction and the radial direction focusing on the opticalaxis of the objective lens 1.

As shown in FIG. 23, in the mechanical component, the both-sides aspectof the tangential direction of the objective-lens holding member 2 isequipped with the focusing coil 3 which is the flat-surface-like drivecoil wound around the axis of the tangential direction, the trackingcoil 4, the radial tilt coil 25, and the tangential-tilt coil 26.

The focusing coil 3, the radial tilt coil 25, and the tangential-tiltcoil 26 are isomorphism-like 4 ream coils, and each generates the thrustof the focusing direction.

However, it is made for the direction of the thrust to have differed bychanging the polarity of the current which flows in each coil.

Namely, for all the four coils for which the focusing coil 3 passes thecurrent the thrust is generated in the same direction and the movableportion is driven to the focusing direction.

The radial tilt coil 25 drives the movable portion to the radial tiltdirection by generating the thrust of the opposite direction in the bothsides in the tracking direction on both sides of the optical axis of theobjective lens 1.

Moreover, the tangential-tilt coil 26 is driven to the tangentialdirection by generating the thrust of the opposite direction on bothsides in the tangential direction on both sides of the optical axis ofthe objective lens 1.

In FIG. 22, the base member 7 includes the magnetic substance, and formsthe yoke section 9 by bending the part.

The magnet 8 for the drive fixed to this yoke section 9 is arranged inthe both sides in the tangential direction of the objective-lens holdingmember 2, and as shown in FIG. 23, the magnetic circuit is formed sothat it may receive at right angles to the focusing coil 3, the trackingcoil 4, the radial tilt coil 25, and the tangential-tilt coil 26 and themagnetic flux may pierce.

The direction perpendicular to the surface which division magnetizationof the magnet 8 is carried out by the magnetization boundary line a ofthe focusing direction, and the magnetization boundary line b of thetracking direction at the shape of a cross joint, and contains thefocusing direction and the tracking direction, and it is magnetized inthe opposite direction in the adjacent range.

Moreover, the drive coils 3, 4, 25, and 26 can be arranged so that themagnetization boundary lines a and b may be straddled, and they can bedriven now in the corresponding direction by passing the current in eachof the drive coils 3, 4, 25, and 26.

As shown in FIG. 22, the end on the side of the stationary members 6 ofthe wire spring 5 is soldered to the elastic board 23 which is havingthe part fixed by the stationary members 6 attached in the base member7.

The E-shaped configuration is carried out, the width of face of thefocusing direction is narrow in 23 a in part, and the elastic board 23can carry out now rotation displacement of the tracking direction bybeing twisted as a main shaft by this partial 23 a.

Corresponding to the tangential tilt operation of the movable portion,stationary-portion part 5 e of the wire spring 5 of the elastic board 23rotates by the edge of the wire spring 5 arranged on the differentposition in the focusing direction being fixed to position 23 b fromwhich the radius of gyration in the rotation part of the elastic board23 differs, respectively.

It is made to have not displaced the spot to the tangential direction bythe tangential tilt operation by arranging the main shaft with which theelastic board 23 is twisted here in the same position as the principalpoint of the objective lens 1 in the focusing direction.

FIG. 24 shows the objective lens drive apparatus of another preferredembodiment of the present invention, and the objective-lens holdingmember 2 holding the objective lens 1 is supported in elasticity in thepresent embodiment 12 with the wire spring 5 which makes the tangentialdirection the lengthening joint.

Spacing is separated to the focusing direction, a total of eight arearranged symmetrically and in parallel four by the tangential directionand each radial direction on each flat surface focusing on the opticalaxis of the objective lens 1, and the wire spring 5 can set the end onthe side of the stationary members 6 of the wire spring 5 in the bothsides in the tangential direction of the movable portion to the elasticboard 24 of the H character configuration by which a part for the centersection is being fixed to the stationary members 6. It is soldered tofour edges 24 a, respectively.

Since it can displace to the tangential direction, the four edges 24 aof the elastic board 24 make the tangential tilt operation of themovable portion possible.

The elastic board 24 of the H character configuration is manufactured bycontour processing by the press die, and the span in the focusingdirection of edge 24 a possessing elasticity cannot be made not muchnarrow on the configuration of the die.

It is necessary to secure the width of face of the slot part about 1 mm.

When performing the tangential tilt operation of the movable portion,the amount of displacement to the direction of the axis of the wirespring 5 becomes the one where the span of the wire spring 5 in thefocusing direction is narrower small.

The radius of gyration between the wire stationary portions on the sideof the movable portion becomes small.

As for the deformation of the elastic board 24, the one where the spanof the wire spring 5 in the focusing direction is narrower becomessmall. That is, the movability will become good.

Then, it is made for the moving-part side to become narrow as much aspossible in the present embodiment to having set widely the span in thefocusing direction of the wire spring 5 as the processable grade at theelastic board 24 side.

Moreover, since the objective lens 1 is generally arranged in the wirespring 5 at the optical disk installation close-attendants side whensetting up narrowly the span on the side of the movable portion ratherthan the stationary member 6 side.

The wire spring 5 a on the side of optical disk installation in thefocusing direction is shown in FIG. 25A. As shown in FIG. 25B, ratherthan only the same include angle makes wire spring 5 b of the oppositeside incline in the opposite direction, respectively.

It is more desirable to install the wire springs 5 a and 5 b rather thanthe center O1 of the span between wire spring 5 a on the side of thestationary members 6 and 5 b, so that the method of center O2 of thespan between wire spring 5 a on the side of the movable portion and 5 bmay be on the optical disk installation side.

When the flexible board fleshed with the reinforcement member ofsuitable thickness is used for the elastic board 24, it becomes possibleto enable it to also perform current supply to the movable portion.

Moreover, resonance can be made to decrease by arranging theviscoelasticity ingredient in the clearance between the movable part ofthe elastic board 24, and the stationary members 6.

FIG. 26 is the perspective diagram of the objective lens drive apparatusfor explaining the preferred embodiment 13 of the present invention.

As the preferred embodiment in which the elastic board 23 is carryingout the E-shaped configuration in the preferred embodiment of FIG. 22,and it is shown in FIG. 24.

It is made for the moving-part side to become narrow to having setwidely the span in the focusing direction of the wire springs 5 a and 5b as the processable grade at the elastic board 23 side.

In FIG. 26, the objective-lens holding member 2 holding the objectivelens 1 is supported in elasticity with the wire springs 5 a and 5 bwhich make the tangential direction the lengthening joint.

The wire springs 5 a and 5 b separate spacing to the focusing directionas mentioned above. It centers on the optical axis of the objective lens1, symmetrically with the tangential direction and each radialdirection.

And a total of eight are arranged with four on each flat surface inparallel, and the end on the side of the stationary members 6 of thewire springs 5 a and 5 b is soldered to the elastic board 23 in theE-shaped configuration by which the part is being fixed to thestationary members 6 attached in the base member 7.

In 23 a, the width of face of the focusing direction is narrow in part,and the elastic board 23 which carried out the E-shaped configurationcan carry out now rotation displacement of the tracking direction bybeing twisted as a main shaft by this partial 23 a.

The tangential tilt operation of the movable portion is made possible bythe edge of the wire spring 5 arranged on the different position in thefocusing direction being fixed to position 23 b from which the radius ofgyration in the rotation part of the elastic board 23 differs,respectively.

Although there are no restrictions on processing like the H mentionedalready character type elastic board 24 in using the elastic board 23which carried out the E-shaped type of the present embodiment, itbecomes easy to be twisted by taking the large action radii of therotation section of the elastic board 23.

Therefore, the movability of direction which takes the large span of thefocusing direction in the wire springs 5 a and 5 b on the side of theelastic board 23 of the tangential tilt direction improves.

The amount of displacement to the shaft orientations of the wire spring5 when the one where the span of the wire of the focusing direction onthe side of the movable portion is narrower carries out the tangentialtilt operation of the movable portion is small.

The radius of gyration of the movable portion and the wire stationaryportion is small.

As for the deformation of the elastic board 23, the one where the spanof the wire of the focusing direction on the side of the movable portionis narrower becomes small. That is, the movability becomes good.

As shown in FIG. 27, in the preferred embodiment 13, the span in thefocusing direction in the wire springs 5 a and 5 b is constituted sothat the span S2 on the side of the movable portion may be narrowed asmuch as possible rather than the span S1 on the side of the elasticboard 23.

Although the present embodiment 13 has composition of the preferredembodiment 11 and the preferred embodiment 12 which combined theconfiguration in part, the effectiveness will be further heightened bythe above reasons by combining both.

It is possible to make it the light spot on the optical disk notdisplace the main shaft with which the elastic board 23 is twisted tothe tangential direction by the tangential tilt operation like thepreferred embodiment 11 by being arranged in the focusing direction inthe same position as the principal point of the objective lens 1.

Moreover, as shown in FIG. 28, the Lw1, and the principal-point m of theobjective lens 1 and the optical disk installation side set the distancebetween the edges on the side of the movable portion of wire spring 5 bof the opposite side to Lw2 for the distance between the edges on theside of the movable portion in wire spring 5 a on the side of theprincipal point m of the objective lens 1, and optical mediainstallation.

When the Ls1, and twist center-of-rotation n and optical diskinstallation side sets distance between the fixed-end sections in wirespring 5 b of the opposite side for the distance between the twistcenter of rotation n of the elastic board 23 in the focusing direction,and the fixed-end section in wire spring 5 a on the side of optical diskinstallation to Ls2.

Also by arranging so that it may be set to Ls1/Ls2=Lw1/Lw2, the crossaction of the tangential direction by the tangential tilt operation canbe reduced, and the fluctuation of the light spot position on theoptical disk can be made small.

In the preferred embodiments, the work attached by carrying out thesolder of the predetermined part is difficult, and positioning the wiresprings 5 a and 5 b using the jig in the case of attachment, since thewire springs 5 a and 5 b are arranged.

Then, it is good to make the wire springs 5 a and 5 b the compositionwhich offsets to the tracking direction so that it may not interfere oneach production at the support state of the objective-lens holdingmember in the preferred embodiment of FIG. 29 from the flat surface as amodification.

In the preferred embodiment, the support center of the trackingdirection does not shift from the center of gravity or driving forcecenter of the movable portion by arranging symmetrically to the flatsurface parallel to the tangential direction including the optical axisof the objective lens 1.

As shown in the perspective diagram which explains the support state ofthe objective-lens holding member in the preferred embodiment 15 shownin FIG. 30 as other examples of composition which avoid the interferenceat the time of attachment, the objective-lens holding member 2 issupported in the end section of the rod-like flat spring 17, and it isthe hinge section about the other edges of the rod-like flat spring 17.

The composition fixed to the stationary member 26 in which 25 isprepared can be considered.

The preferred embodiment 15 is the rod-like flat spring manufactured byetching or precision sheet metal work.

It arranges on the both sides aspect in the tracking direction of themovable portion by making into the direction of the flat surface theflat surface which makes the tracking direction the perpendicular for17.

The rod-like flat spring 17 excises the unnecessary part by it, afterthickness is making it about 50 micrometers and really casts the oneplate-like member by this example to the objective-lens holding member 2and the stationary member 26.

The hinge section 25 of the hinge configuration in which the partrotates the tracking direction as a shaft is formed in the stationarymember 26, and rotation of the fixed-end section in the stationarymember 26 of the rod-like flat spring 17 is attained.

By doing in this way, it is each rod-like flat spring.

The positioning accuracy to the span between 17 or the objective-lensholding member 2, and the stationary member 26 can improve, andstruggling between the individuals can also be made small.

FIG. 31 is a diagram for explaining the preferred embodiment of theoptical pickup device of the present invention which incorporates theobjective lens drive apparatus of the preferred embodiment of FIG. 1.

In FIG. 31, 31 is the light source, 32 is the collimator lens, 33 is thebeam splitter, 34 is the starting mirror, 35 is the focusing lens, 36 isthe rod-like lens, 37 is the light-receiving component, 38 is theoptical disk, and 39 is the objective lens drive apparatus of thepreferred embodiment.

The divergent light from the light source 31 turns into parallel lightby the collimator lens 32.

Then, it passes along the beam splitter 33 and the starting mirror 34bends.

The parallel light bent by the starting mirror 34 is the objective lensdrive apparatus 3.

Incidence is carried out to the objective lens 1 of 8, and the lightspot S is formed on the optical disk 38.

After the reflected light of the light spot S from the optical disk 38is deflected by the beam splitter 33 and passes along the focusing lens35 and the rod-like lens 36, incidence of it is carried out to thelight-receiving component 37.

Thus, it arranges so that the reflected light of the light spot S on theoptical disk 38 may carry out incidence to the light-receiving component37.

By generating the control signal and outputting to the objective lensdrive apparatus 39 by objective-lens control means (not shown), such asthe operation processing section, based on the signal acquired with thelight-receiving component 37, the focusing coil and the tracking coilare driven and the information recorded on the optical disk 38 can bereproduced by making the objective lens 1 follow to the optical disk 38.

Furthermore, by the tilt sensor which is not illustrated detecting theinclination of the optical disk 28, and passing the current according toit in the tilt coil (not shown) of the objective lens drive apparatus39, the objective lens 1 is made to incline to the optical disk 38, andtilt compensation is performed.

Here, the objective lens drive apparatus 39 is this objective lens driveapparatus 3, as it is the objective lens drive apparatus of thecomposition of each preferred embodiment explained by FIG. 1-FIG. 30 andbeing mentioned already.

Even when rotating surface blur, eccentricity, and the large opticaldisk 38 of the curvature at high speed by using 9, it becomes possibleto make the objective lens 1 follow to the optical disk 38. That is,good recording or reproduction of the optical disk can be carried out athigh speed.

FIG. 32 shows an optical disk drive in which the optical pickup deviceof FIG. 31 is provided. FIG. 33 is a front view of the optical diskdrive of FIG. 32.

In FIG. 32 and FIG. 33, reference numeral 40 indicates the opticalpickup device explained with FIG. 31, and the optical pickup device 40includes the light source 31, the collimator lens 32, the rod-like lens36, the light-receiving component 37, the objective lens drive apparatus39, etc.

Furthermore, reference numeral 41 indicates the housing of the opticaldisk drive, 42 indicates the cushion rubber, 43 indicates the spindlemotor which is the rotation drive means of the optical disk 38, 44indicates the seek rail, and 45 indicates the pickup module base. Thepickup module base 45 is attached to the housing 41 of the optical diskdrive through the cushion rubber 42.

The spindle motor 43 which carries out the rotation drive of the opticaldisk 38 is installed in the pickup module base 45.

Moreover, the optical pickup device 40 is carried in the seek rail 44attached in the pickup module base 45.

The movement drive of the optical pickup device 40 is carried out in theradial direction of the optical disk 28 along the seek-rail 44 by thepickup drive means including the seeking motor (not shown).

The optical pickup device 40 provided in the optical disk drive shown inFIG. 32 and FIG. 33 can treat with the optical disk 38 about theobjective lens 1, even when the optical disk 38 rotated at high speedhas surface blur, eccentricity or a large curvature of the surface, andit is possible to make the optical pickup device follow to the opticaldisk 38.

Therefore, it enables the optical disk drive of this example of thepreferred embodiment to perform recording/reproduction at high speed.

As described above, according to the objective lens drive apparatus ofthe present invention, it is possible to correct the inclination errorof the optical disk and the objective lens. By making it possible togenerate the driving force which can follow the optical disk underhigh-speed rotation to carry out the independent drive at each shaftorientations, the movability of the tangential tilt direction can bemade good, and the sensibility can be made small.

The optical disk drive of the present invention can perform stablecontrol and it sets to the objective lens drive apparatus dealing withinclination compensation. The cross talk between the drive shafts whichare easy to pose the problem can be reduced. Specifically, it ispossible to reduce the cross talk including the cross talk of thetangential rotation direction generated by focusing translation drive,the cross talk of the tangential movement direction generated byfocusing or tracking translation drive, and the cross talk of thetangential movement direction generated by the tangential rotationdrive.

Next, FIG. 36 shows the objective lens drive apparatus of anotherpreferred embodiment of the invention. FIG. 37 is a top view of theobjective lens drive apparatus of FIG. 36. FIG. 38 is a side view of theobjective lens drive apparatus of FIG. 36. FIG. 39 is an exploded viewof the coils, yokes and magnets in the objective lens drive apparatus ofFIG. 36. FIG. 40A through FIG. 40D are diagrams for explaining the tiltcompensation operation.

The objective lens 202 is held by the objective-lens holding member 203in the objective lens drive apparatus 201 of the present embodiment.

The objective-lens holding member 203 is elastically supported by fourwire springs 204 a, 204 b, 204 c and 204 d which are the rod-likeelastic support members. The through hole 205 of the shape of an anglemade to penetrate in the vertical direction is formed in a part ofobjective-lens holding member 203.

The focusing coils 206 a and 206 b and the tracking coils 207 a and 207b which are the driving coils by which the wire is wound to the shape ofa flat-surface coil are fixed to the center section of the through hole205.

Movable portion 208 is constituted by these objective lenses 202, theobjective-lens holding member 203, the focusing coils 206 a and 206 b,and the tracking coils 207 a and 207 b.

Moreover, in the objective lens drive apparatus 201 of the presentembodiment, the group base 209 made from the magnetic substance whichmakes a part of stationary member is formed.

The yokes 210 a and 210 b which project in the through hole 205 on bothsides which interpose the coils 206 a, 206 b, 207 a, and 207 b areformed in one by bending some group bases 209.

Inside the yokes 10 a and 10 b, the coils 6 a, 6 b, 7 a and 7 b and themagnets 11 a and 11 b for the drive by the permanent magnet which formsthe magnetic circuit with the yokes 10 a and 10 b so that the magneticflux may pass through the inside are being fixed.

The relation between the coils 6 a, 6 b, 7 a, and 7 b and the magnets 11a and 11 b for the drive is explained with reference to FIG. 39.

The magnets 11 a and 11 b for the drive are divided into four sectionsalong with the cross-like magnetization boundary lines a and b (4-polemagnetization).

The magnetization direction is magnetized in the range and the oppositedirection which are perpendicular (the direction of theZ-axis-direction=jitter), and adjoin each other to the surfacecontaining the two axial directions of the direction of the focus(Y-axis direction), and the tracking direction (X-axis direction).

Furthermore, the magnets 11 a and 11 b for the drive are arranged sothat the magnetization direction of the part which faces mutually onboth sides of the focusing coils 6 a and 6 b and the tracking coils 7 aand 7 b may be in agreement.

Moreover, the four wire springs 4 a-4 d have the axial direction inparallel to the direction (the direction of the Z-axis-direction)perpendicular to the surface containing the two axial directions of thefocusing direction (Y-axis direction) and the tracking direction (X-axisdirection).

On the flat surface (the first flat surface of the direction near theprincipal point of the objective lens 2) of the imagination whichintersects perpendicularly in the direction of the focus, make thetracking direction estrange the wire springs 4 a and 4 b, and they arearranged in parallel.

The tracking direction is made to estrange the wire springs 4 c and 4 don the flat surface (the second flat surface) of the imagination whichintersects perpendicularly in the direction of the focus in thedifferent position from the first flat surface, they are arranged inparallel, and support movable portion 8 (objective lens 2) in elasticityto the two axial directions of the direction of the focus, and thetracking direction.

The end-winding child board 12 is fixed to the both sides of theobjective-lens holding member 3, and the wire springs [4 a-4 d] end sideis being fixed to these end-winding child boards 12 by soldering.

The wire springs 4 a-4 d other end edge is being fixed to the elasticboard 14 as a movable portion which penetrated the stationary member 13which is fixed on the group base 9 and constitutes a part of stationarymember, and is attached in this stationary member 13 by soldering.

It fills up with the silicon system gel for making the wire springs inthe stationary member 13 4 a-4 d through hole part dump the wire here,and here, preventing resonance etc.

Moreover, the wire springs 4 a-4 d are formed of the conductiveingredient, and current supply of them is enabled at Coils 6 a, 6 b, 7a, and 7 b through the elastic board 14 of board composition, the wiresprings 4 a-4 d, and the end-winding child board 12.

Moreover, while the elastic board 14 is attached on heights 13 a of thestationary member 13, the ends side notches 14 a and 14 b, the wiresprings 4 a-4 d, it is constituted independently every as thedeformation sections 15 a-15 d which can deform in the direction of thejitter.

It is fixed to the wire springs 4 a-4 d on the stationary-portion sideat the one end edge, and the deformation sections 15 a-15 d, it issupported by possible displacement in the longitudinal direction(rod-like lengthening-joint=the direction of the jitter).

Moreover, near the deformation sections 15 a-15 d, it is the drivesource 16 is provided for tilt compensation.

The flat-surface coil-like coils 17 a-17 d for the tilt drive with whichthe drive source 16 for tilt compensation is fixed to each of thedeformation sections 15 a-15 d near the edge. The pole of N and S is setup for the permanent magnet 18 a fixed to some group bases 9 in theposition which is set up in the direction of the jitter and carries outproximity opposite at the coils 17 a and 17 c for the tilt drive. Thepositions which similarly the pole of N and S is set up in the directionof the jitter, and carry out proximity opposite at the tilt drive coils17 b and 17 d are contained with the permanent magnet 18 b fixed to somegroup bases 9.

The control to the coils 17 a-17 d for the tilt drive of eachdeformation section 15 a-15 d is made possible to make the displacementin the direction of the jitter individually, and to carry outdisplacement in the opposite direction thereof or the direction of thejitter depending on the energization direction.

In addition, in FIG. 38, reference numeral 19 indicates the opticaldisk, and reference numeral 20 indicates the starting prism.

In such composition, the tilt compensation operation of the objectivelens 2 will be explained.

The displacement of the deformation sections 15 a and 15 b which passthe current of the same direction and correspond to the coils 17 a and17 b for the tilt drive is made to carry out in the direction (thedirection of outside) of P, as shown in FIG. 5C.

In connection with this, it displaces in the direction (the direction ofoutside) of P whose other end therefore, wire (also itself) and edge ofthe wire springs 4 a and 4 b on the first flat surface currently fixedto the deformation sections 15 a and 15 b are in the longitudinaldirection.

As shown in FIG. 5C, to the coils 17 c and 17 d for the tilt drive, thecoils 17 a and 17 b for tilt drive is about the deformation sections 15c and 15 d which pass the current of the same direction to the reversepolarity, and correspond to it. The displacement is made to carry out inthe direction (the inner direction) of Q, as shown in FIG. 5C.

In the present embodiment, it displaces in the direction (the innerdirection) of Q whose wire springs on the second flat surface currentlyfixed to the deformation sections 15 c, 15 c, 4 c and 4 d at the otherend, the wire springs are in the longitudinal direction.

That is, displacement is carried out so that the wire springs, i.e., thewire springs 4 a and 4 b and the wire springs 4 c and 4 d, arranged inthe position (the first flat surface and second flat surface) where thedirections of the focus differ may offset the wire springs 4 a-4 d otherend edge of each other to the longitudinal direction (the direction ofthe jitter).

As shown in FIG. 5C, rotation displacement of the movable portion 8supported at the wire springs 4 a-4 d end side can be carried out to thetangential direction, and therefore, the compensation of the tangentialtilt of the objective lens 2 is attained.

What is necessary is just to make the opposite direction offset at thetime of the compensation of the tangential tilt of the oppositedirection.

For this reason, it is necessary to be fixed to the wire springs 4 a-4 dstationary-portion side, and also just to have the drive source 216 fortilt compensation in which enable displacement of the one end edge inthe direction of the jitter by each deformation sections 15 a-15 d ofthe elastic board 14, and the displacement is made to perform, thecompensation of the tangential tilt can be realized, without giving theload to the movable portion 8.

Moreover, the thing for which the tangential tilt is corrected bycarrying out displacement of the wire springs 4 a-4 d other end edge tothe longitudinal direction with high rigidity. The displacement of theother end edge can also be told to the end side as it is, it becomeswhat has the good flattery nature on the side of the movable portion 8supported at the end side which are the wire springs 4 a-4 d or goodresponsibility, and the tangential-tilt compensation which can respondalso to high-speed operation is attained.

A description will be given of another preferred embodiment of thepresent invention with reference to FIG. 41 through FIG. 43B.

In the present embodiment, the elements which are essentially the sameas corresponding elements in the previous embodiment are designated bythe same reference numerals, and a description thereof will be omitted.

When the movable portion 208 is supported by the cantilever type similarto the previous embodiment, in connection with the tangential drive, thepresent embodiment shows the composition in which the countermeasure istaken in consideration of the point that the objective lens 2 displacesin the direction of the focus as shown in FIG. 40D.

In the objective lens drive apparatus of the present embodiment, theobjective lens 202 is considered as the composition of centralarrangement, and the wire spring, the elastic board, and the drivesource for tilt compensation are established in the both sides of thedirection of the jitter of the movable portion 208 so that it may becomesymmetrical to the straight line of the tracking direction passingthrough the objective-lens center.

Specifically, in the present embodiment, the wire springs 204 a-204 d,the elastic board 214 (the deformation sections 215 a-215 d), the wiresprings 222 a-222 d of the same composition corresponding to the source216 (the tilt drive coils 217 a-217 d and the permanent magnets 218 aand 218 b) for the tilt drive compensation, the elastic board 223 (thedeformation sections 224 a-224 d) and the source 225 (the tilt drivecoils 226 a-226 d and the permanent magnets 27 a and 27 b) for the tiltdrive compensation are provided in the reverse side in the direction ofthe jitter.

The stationary member 228 corresponding to the stationary member 213 isalso provided.

Therefore, in the present embodiment, the wire springs 204 a, 204 b, 222a, and 222 b are arranged on the first flat surface, and the wiresprings 204 c, 204 d, 222 c, and 222 d are arranged on the second flatsurface.

In addition, with the present embodiment, the yokes 210 a and 210 b andthe magnets 211 a and 211 b for the drive are arranged in the both sidesof the direction of the jitter on both sides of the objective lens 202,and the tracking coils 207 a and 207 b are also arranged in both sides.

But about the focusing coil, it replaces with the flat-surface coil-likefocusing coils 206 a and 206 b, and the focusing coil 229 by which thewire is wound to the circumference of movable portion 208 in the shapeof a cylinder is used.

In such composition, tilt compensation operation of the objective lens202 will be explained with reference to FIG. 42A-FIG. 42C.

The displacement of the deformation sections 215 a, 215 b, 224 a, and224 b which correspond by control to the coils 217 a, 217 b, 226 a, and226 b for the tilt drive is made to carry out in the direction of P, asshown in FIG. 42C.

In the present embodiment, it displaces in the direction of P whoseother end therefore, wire (also itself) and edge of the wire springs 204a, 204 b, 222 a, and 222 b on the first flat surface currently fixed tothe deformation sections 215 a, 215 b, 224 a, and 224 b are in thelongitudinal direction.

On the other hand, the displacement of the deformation sections 215 c,215 d, 224 c, and 224 d which correspond by control to the coils 217 c,217 d, 226 c, and 226 d for the tilt drive is made to carry out in thedirection of Q, as shown in FIG. 40C.

In the present embodiment, it displaces in the direction of Q whose wiresprings on the second flat surface currently fixed to the deformationsections 215 c, 215 c, 224 c, 224 d, 204 c, 204 d, 222 c, and 222 d atthe other end, the wire springs are in the longitudinal direction.

Namely, the wire springs arranged in the position (the first flatsurface and second flat surface) where the directions of the focusdiffer in the wire springs 204 a-204 d and the other end edge (222 a-222d).

That is, displacement is carried out so that the wire springs 204 a and204 b, the wire springs 204 c and 204 d and the wire springs 222 a and222 b, and the wire springs 222 c and 222 d may offset mutually to thelongitudinal direction (the direction of the jitter).

As shown in FIG. 40C, rotation displacement of the wire springs 204a-204 d and the movable portion 208 supported at the end 222 a-222 dside can be carried out to the tangential direction, and therefore, thecompensation of the tangential tilt of the objective lens 202 isattained.

Of course, what is necessary is just to make the opposite directionoffset at the time of the compensation of the tangential tilt of theopposite direction.

By the way, when it decomposes into every one side and suchtangential-tilt compensation operation is considered, it comes to beshown in FIG. 43A and FIG. 43B.

Namely, considering tangential-tilt compensation operation on the sideof the wire springs 204 a-204 d, as opposed to the direction crossaction of the jitter occurring in the direction shown by the arrow headR to the objective lens 202 of the movable portion 208.

Considering tangential-tilt compensation operation on the side of thewire springs 222 a-222 d, by the direction cross action of the focusoccurring to the opposite direction as shown by the arrow head S to theobjective lens 202 of the movable portion 208, and offsetting thesedirection cross actions of the focus.

The tangential-tilt compensation operation which the fluctuation of thedirection of the focus does not produce as the whole is attained.

Moreover, in order to reduce the direction cross action of the jitteraccompanying tangential-tilt compensation operation, in composition asshown in the form of the first operation, the amount of displacement tothe direction of the jitter of the other end edge of the wire springs204 a and 204 b of the direction near the principal-point side of theobjective lens 202.

It is possible to make it bring the rotation center for tangential-tiltcompensation close to the principal point of the objective lens 202 asmuch as possible by making it smaller than the amount of displacement tothe direction of the jitter of the wire springs 204 c and 204 d of theone distant from the principal-point side of the objective lens 202 atthe other end edge.

In this case, the thing for which reinforcement (rigidity) of thedeformation sections 215 a and 215 b is made stronger than deformationsections 215 c and 215 d reinforcement (rigidity) although giving thedifference to the amount can also be realized, according to adjustmentof the amount of drive with the coils 217 a, 217 b, 217 c, and 217 d forthe tilt drive, it can realize more easily.

Moreover, making the wire springs 204 a and 204 b, the wire springs 204c and 204 d and the wire springs 222 a and 222 b, and the wire springs222 c and 222 d offset in the direction of the jitter in tangential-tiltcompensation operation, the other end edge of the wire springs 204 a,204 b, 222 a, and 222 b may be position fixation.

FIG. 44 shows such modification in which it is the wire springs 204 c,204 d, 222 c and 222 d at the other end edge, the deformation sections215 c, 215 d, 224 c and 224 d, it fixes in the direction of the jitter(the longitudinal direction) possible, the coils 217 c, 217 d, 226 c,and 226 d for the tilt drive, and the permanent magnets 218 a, 218 b,227 a, and 227 b.

In addition, the first flat surface of the imagination in which the wiresprings 204 a, 204 b, 222 a, and 222 b are arranged is set as theposition passing through the principal point of the objective lens 202.

The displacement only of the deformation sections 215 c, 215 d, 224 c,and 224 d is made to carry out in the direction of the jitter with thecoils 217 c, 217 d, 226 c, and 226 d for the tilt drive, and thepermanent magnets 218 a, 218 b, 227 a, and 227 b at the time of thecompensation of the tangential tilt, and the displacement only of thewire springs other end edge is made to carry out in the direction of thejitter (the longitudinal direction).

The wire springs 204 a, 204 b, 222 a and 222 b side is fixed and it doesnot displace the movable portion 208 the near principal point of theobjective lens 202, the rotation center carrying out the displacementfor tangential-tilt compensation, the occurrence of the direction crossaction of the jitter can be prevented.

In addition, this method is applicable similarly in the case of thesingle-sided support method like the previous embodiment of FIG. 36.

Next, a description will be given of another preferred embodiment of thepresent invention with reference to FIG. 45 and FIG. 46A-FIG. 46D.

The objective lens drive apparatus of the present embodiment takes intoconsideration not only the compensation of the tangential tilt but thecompensation of the radial tilt.

The straight line of the direction of the jitter where the wire springs204 a-204 d and 222 a-222 d pass along the objective-lens 202 opticalaxis by the objective lens drive apparatus of this embodiment on eachflat surface although fundamental composition applies to the objectivelens drive apparatus shown with the present embodiment, and it is madeto incline and is arranged.

The configuration to which the wire springs 204 a, 204 b, 222 a, and 222b are seen from the focus to the direction of the jitter which passesalong the objective-lens 202 optical axis on the first flat surface, itsmoving-part 208 side is narrow, and the elastic board 214 and 223 sidebecomes large, and it is made to incline and is arranged.

In the direction of the focus to the direction of the jitter which isthe same also as for the wire springs 204 c, 204 d, 222 c, and 222 d,and passes along the objective-lens 202 optical axis on the second flatsurface, and elastic board 214 and 223 side becomes the movable portionside narrow widely, and it is made to incline and is arranged.

Also in such composition, it can carry out by the same control as thecase where it mentions above, at the time of the compensation of thetangential tilt.

That is, the displacement of the deformation sections 215 a, 215 b, 224a, and 224 b which correspond by control to the coils 217 a, 217 b, 226a, and 226 b for the tilt drive as well as the case of FIG. 42C is madeto carry out in the direction of P.

In connection with this, it displaces in the direction of P whose otherend therefore, wire and edge of the wire springs 204 a, 204 b, 222 a,and 222 b on the first flat surface currently fixed to the deformationsections 215 a, 215 b, 224 a, and 224 b are in the longitudinaldirection.

On the other hand, the displacement of the deformation sections 215 c,215 d, 224 c, and 224 d which correspond by control to the coils 217 c,217 d, 226 c, and 226 d for the tilt drive as well as the case of FIG.42C is made to carry out in the direction of Q.

In connection with this, it displaces in the direction of Q whose wiresprings on the second flat surface currently fixed to the deformationsections 215 c, 215 c, 224 c, 224 d, 204 c, 204 d, 222 c, and 222 d atthe other end, the wire springs are in the longitudinal direction.

Namely, the wire springs arranged in the position (the first flatsurface and second flat surface) where the directions of the focusdiffer in the wire springs 4 a-4 d and the other end edge (222 a-222 d).

That is, the displacement is carried out so that the wire springs 204 aand 204 b, the wire springs 204 c and 204 d and the wire springs 222 aand 222 b, and the wire springs 222 c and 222 d may offset mutually tothe longitudinal direction (the direction of the jitter).

The rotation displacement of the wire springs 204 a-204 d and themovable portion 208 supported at the end 222 a-222 d side can be carriedout to the tangential direction by this, and, therefore, thecompensation of the tangential tilt of the objective lens 202 isattained.

On the other hand, the compensation operation of the radial tilt will beexplained with reference to FIG. 46A-FIG. 46D.

In this case, what is necessary is just to carry out displacementrelatively so that the groups may offset them mutually to thelongitudinal direction, using as the group the wire springs arranged inthe position where it is arranged in the position where the trackingdirections differ, and the directions of the focus differ the other endedge of the wire spring fixed to the stationary-portion side.

For example, the displacement of the deformation sections 215 a, 215 d,224 b, and 224 c which correspond by the control to the tilt drive coils217 a, 217 d, 226 b, and 226 c is made to carry out in the direction ofP, as shown in FIG. 46A-FIG. 46D.

In the present embodiment, it displaces in the direction of P whoseother end therefore, wire and edge of the wire springs 204 a, 204 d, 222b, and 222 c currently fixed to the deformation sections 215 a, 215 d,224 b, and 224 c are also the direction of the jitter (the longitudinaldirection).

On the other hand, the control to the coils 217 b, 217 c, 226 a, and 226d for the tilt drive makes the displacement of the deformation sections215 b, 215 c, 224 a, and 224 d which correspond as opposition controlcarry out in the direction of Q, as shown in FIG. 46B.

In the present embodiment, it displaces in the direction of Q whose wiresprings which are being fixed to the deformation sections 215 b, 215 c,224 a, 224 d, 204 b, 204 c, 222 a, and 222 d at the other end the wiresprings are in the direction of the jitter (the longitudinal direction).

In such operation, each of the wire springs 204 a-204 d and 222 a-222 dis inclined, and the vector is as shown in FIG. 46A in the connectionsection to the movable portion 208, and the partial output to thetracking direction according to the direction is also produced.

As shown in FIG. 46C, when the partial-output component of this trackingdirection is considered in the direction of the jitter, the moment torotate in the radial tilt direction the movable portion 208 appears asshown in FIG. 46C. As shown in FIG. 46D, the compensation of the radialtilt of the movable portion 208 (the objective lens 202) is possible.

What is necessary is just to make the opposite direction drive at thetime of the compensation of the radial tilt of the opposite direction.

Therefore, if it controls combining the compensation of the tangentialtilt, the compensation of the tangential tilt of the objective lens 202and the radial tilt will be attained.

For this reason, it carries out inclination arrangement in thesymmetrical state to the straight line of the wire springs 204 a-204 d,the first which intersect perpendicularly 222 a-222 d in the directionof the focus, and the direction of the jitter which passes along thelens center on the second flat surface and is fixed to thestationary-portion side the one end edge the deformation sections 215a-215 d and 224 a-224 d carrying out the sources 216 and 225, thecompensation of the tangential tilt or the radial tilt can be realizedwithout giving the load to the movable portion 208.

Moreover, the thing for which the compensation of the tangential tilt orthe radial tilt is performed by carrying out displacement of the wiresprings 204 a-204 d and the other end edge (222 a-222 d) to thelongitudinal direction (the direction of jitter) with high rigidity.

It becomes what has the good flattery nature on the side of wire springs204 a-204 d, 222 a-222 d the movable portion 208 supported at the endside or good responsibility, and the compensation of the tangential tiltwhich can respond also to high-speed operation, or the radial tilt isattained.

In addition, although cross action of the tracking direction may occurin the objective lens drive apparatus of the present embodiment when thepositions of the center of rotation of the movable portion 208 and theprincipal point of the objective lens 202 differ at the time to theradial direction.

As the countermeasure, the wire springs 204 a, 204 b, 222 a, 222 b aremade to arrange in the first direction near the principal point of theobjective lens 202, and the displacement of the wire springs 204 c, 204d, 222 c, and 222 d in the longitudinal direction are made to arrange inthe second direction where the amount is distant from the principalpoint of the objective lens 202 in the longitudinal direction if it ismade to become smaller than the amount.

Displacement operation for radial tilt compensation can be made to beable to perform as much as possible by the ability setting near theprincipal point of the objective lens 202 as the rotation center, andthe direction cross action of the track can be made to mitigate.

This is the same also about the direction cross action of the jitter atthe time of tangential-tilt compensation.

It is possible to make it the wire springs 204 a, 204 b, 222 a and 222 bthe amount of displacement in the longitudinal direction become small asmeans for this by adjustment of the amount of drives by the drivesources 216 and 225 for tilt compensation.

The degree of slope angle of the wire springs 204 a, 204 b, 222 a, and222 b made to arrange on the first direction near the principal point ofthe objective lens 202 is made smaller than the degree of slope angle ofthe wire springs 204 c, 204 d, 222 c, and 222 d made to arrange on thesecond direction distant from the principal point of the objective lens202.

Even if it is the amount of the same drive, it is possible to make thewire springs 204 a, 204 b, 222 a and 222 b arranged with the amount ofdisplacement in the longitudinal direction become small.

It is possible to make it arranged with the degree of slope angle=0. Inthe extreme example, the wire springs 204 a, 204 b, 222 a, and 222 b aremade to arrange on the first direction near the principal point of theobjective lens 202 in parallel.

Moreover, in compensation operation of the radial tilt or the tangentialtilt, as long as it is relative to make the wire spring offset in thedirection of the jitter, it may be good, for example, the other end edgeof the wire springs 204 a, 204 b, 222 a, and 222 b may be positionfixation.

It is fixed in the direction of the jitter (the longitudinal direction)with possible displacement by the deformation sections 215 c, 215 d, 224c and 224 d. Namely, in the example shown in FIG. 44 applyingcorrespondingly the wire springs 204 c, 204 d, 222 c and 222 d on theother end edge is possible.

The displacement drive is enabled with the coils 217 c, 217 d, 226 c,and 226 d for the tilt drive, and the permanent magnets 218 a, 218 b,227 a, and 227 b.

It is possible to make it set the first flat surface of the imaginationin which the wire springs 204 a, 204 b, 222 a, and 222 b are arranged asthe position passing through the principal point of the objective lens202.

According to this, displacement operation the object for tangential-tiltcompensation and for radial tilt compensation can be made to be able toperform by the ability setting near the principal point of the objectivelens 202 as the rotation center, and, therefore, the direction crossaction of the jitter and the direction cross action of the track can beprevented.

In addition, in the present embodiment, the example of the both-sidessupport method has been explained to the movable portion 208 accordingto the previous embodiment, and in the case of the single-sided supportmethod according to the previous embodiment, it is applicable similarly.

Moreover, it is possible to make the wire springs 204 a-204 d and 222a-222 d incline in the shape of a character to which it sees in thedirection of the focus conversely although the wire springs 204 a-204 dand 222 a-222 d are made to incline so that it may see in the directionof the focus with this embodiment and the elastic board 214 and 223 sidemay become the movable portion 208 side narrow widely, and the elasticboard 214 and 223 side.

Moreover, although the example which attaches the coil in the elasticboards 214 and 223 side, and attaches the magnet in the group base 209side is explained the drive sources 216 and 225 for tilt compensationwith the present embodiment, the coil is attached in the group base 209side, and it is possible to make it attach the magnet in the elasticboards 214 and 223 side conversely.

Furthermore, in order to reduce components mark and to raise attachmentnature, the elastic boards 214 and 223 may be formed with the printcoil, or you may constitute so that the magnetic leakage flux of themagnets 211 a and 211 b for the drive for the moving-part drive maypierce through the coil for the tilt drive.

Moreover, the drive source for tilt compensation is provided as well asin the combination of such a magnet and a coil as in FIG. 47.

The piezoelectric devices 232 a-232 d made to intervene individuallybetween each deformation sections 215 a-215 d of the elastic board 214and the stationary member 213 are used as a drive source for tiltcompensation.

Displacement of the each deformation sections 215 a-215 d leading edgeis carried out, and it may be made to carry out displacement of the wiresprings 204 a-204 d other edge to the longitudinal direction by theslight drive of the piezoelectric devices 232 a-232 d. According tothis, highly precise tilt compensation is attained.

A description will be given of another preferred embodiment of thepresent invention wither reference to FIG. 48.

In the present embodiment, the example of application to the opticalpickup device 242 equipped with the objective lens drive apparatus ofone preferred embodiment of the present invention is shown.

The divergent light, output from the light source 243, such as asemiconductor laser carried in the optical pickup device 242, isconverted into the parallel light by the collimator lens 244.

Then, it passes along the beam splitter 245 and the starting mirror 246(it is equivalent to the starting prism 220) bends.

Incidence of the parallel light bent by the starting mirror 246 iscarried out to the objective lens 202 of the objective lens driveapparatus 241 carried in the optical pickup device 242, and it forms thespot on the optical disk 219.

After the reflected light of the spot changes the direction and polaritywhich came by the beam splitter 245 and passes along the condenser lens247 and the rod-like lens 248, it is incident to the 4-divisionlight-receiving component 249.

It arranges so that the reflected light of the spot on the optical disk219 may carry out incidence to the 4-division light-receiving component249.

The information on the optical disk 219 can be acquired by making theobjective lens 202 follow to the optical disk 219 by carrying out basedon the signal acquired with the 4-division light-receiving component249, and driving the focusing coils 206 a and 206 b and the trackingcoils 207 a and 207 b of the objective lens drive apparatus 241.

The light-receiving optical system 250 is constituted by the condenserlens 247, the rod-like lens 248, and the 4-division light-receivingcomponent 249.

Furthermore, the objective-lens control drive (not shown) which outputsthe drive signal over the objective lens drive apparatus 241 based onthe received light signal of the 4-division light-receiving component249 is also provided.

The objective lens drive apparatus 241 in the optical pickup device 242is one preferred embodiment of the present invention described above,and the objective lens 202 is made to follow to the optical disk 219 bythe objective lens drive apparatus 241 as mentioned above and theinformation on the optical disk 219 is read. The control of theinfluence of the tangential tilt or the radial tilt of the objectivelens drive apparatus 241 is attained at the time of the objective-lensdrive.

A description will be given of another preferred embodiment of thepresent invention with reference to FIG. 49 and FIG. 50.

In the present embodiment, the example of application to the opticaldisk drive which incorporates the optical pickup device 242 mentionedabove is shown.

As shown in FIG. 49 and FIG. 50, the pickup module base 253 is installedin the housing 251 of the optical disk drive through the rubber cushion252.

The spindle motor 254 as a rotation drive system which rotates theoptical disk 219 is fixed to the pickup module base 253.

Moreover, the optical pickup device 242 is provided with the seek rail255 attached in the pickup module base 253.

Movement to radial of the optical disk 219 of the optical pickup device242 is enabled in the seek rail 255.

The optical pickup device 242 carried in the optical disk driveconcerned is the optical pickup device which is mentioned above andwhich is explained with the form of the fourth operation, and is theoptical pickup device in which few control of the influence of thetangential tilt or the radial tilt is possible at the time of theobjective-lens drive. Therefore, when it is easy to be influenced of thetilt like DVD, the convenient optical disk drive can be offered.

Next, FIG. 51 shows the composition of the optical disk drive of anotherpreferred embodiment of the present invention.

The optical disk drive 320 of FIG. 51 includes the spindle motor 322 forcarrying out the rotation drive of the optical disk 315, the opticalpickup device (OPD) 323, the laser control circuit 324, the encoder 325,the motor driver 327, the reproduction signal-processing circuit (RSP)328, the servo controller 333, the buffer RAM 334, the buffer manager337, the interface 338, the ROM 339, the CPU 340, the RAM 341, and thetilt sensor 342, etc.

In addition, the arrow head in FIG. 51 does not show the flow of thetypical signal or information, and does not express connection-relatedall of each block.

Moreover, in the present embodiment, the information storage mediumbased on the specification of the DVD (digital versatile disc) system asan example is used as the optical disk 315.

The optical pickup device 323 is equipment for receiving the reflectedlight from the record surface of the optical disk 315 while irradiatinglaser light to the predetermined position of the recording surface ofthe optical disk 315 in which the track in the spiral orconcentric-circle formation is formed.

The reproduction signal processing circuit 328 includes the first I/Vamplifier 328 a, the servo signal detector 328 b, the wobble-signaldetector 328 c, the RF signal detector 328 d, the decoder 328 e, thesecond I/V amplifier 328 f, and the tilt detector 328 g, as shown inFIG. 52.

The first I/V amplifier 328 a performs amplification with apredetermined gain while it changes into the voltage signal the currentsignal which is the output signal of the optical pickup device 323.

The servo signal detector 328 b detects servo signals (the focusingerror signal, tracking error signal, etc.) based on the voltage signalfrom the first I/V amplifier 328 a. The servo signal detected isoutputted to the servo controller 333.

The wobble-signal detector 328 c detects the wobble signal based on thevoltage signal from the first I/V amplifier 328 a.

The RF signal detector 328 d detects the RF signal based on the voltagesignal from the first I/V amplifier 328 a.

The decoder 328 e extracts ADIP (Address In Pregroove) information, thesynchronizing signal, etc. from the wobble signal detected by thewobble-signal detector 328 c.

The ADIP information extracted is outputted to the CPU 340, and thesynchronizing signal is outputted to the encoder 325.

Moreover, after the decoder 328 e performs recovery processing,error-correction processing, etc. to the RF signal detected by the RFsignal detector 328 d, it is stored in the buffer RAM 334 through thebuffer manager 337 as reproduction data.

In addition, when reproduction data are music data, it is outputted tothe external audio instrument.

The second I/V amplifier 328 f performs amplification with apredetermined gain while it changes into the voltage signal the currentsignal which is the output signal of the tilt sensor 342.

The tilt detector 328 g detects the information about the media tiltbased on the voltage signal from the second I/V amplifier 328 f. Theinformation about the media tilt detected is outputted to the servocontroller 333 as the tilt information signal.

Referring back to FIG. 51, the servo controller 333 generates thevarious control signals for controlling the optical pickup device 323based on the servo signal, and outputs them to the motor driver 327.

Moreover, the servo controller 333 generates the tilt compensationsignal for correcting the inclination of the record side based on thetilt information signal, and outputs it to the motor driver 327.

The motor driver 327 outputs the drive signal to the optical pickupdevice 323 based on the control signal and tilt compensation signal fromthe servo controller 333.

Moreover, the motor driver 327 outputs the drive signal to the spindlemotor 322 based on directions of CPU 340.

The buffer manager 337 notifies I/O of the data to the buffer RAM 334 toCPU 340 that it manages and the accumulated amount of data turns intothe predetermined amount.

It is written in synchronizing with the synchronizing signal from thereproduction signal processing circuit 328, and outputs the signal tothe laser control circuit 324 while the encoder 325 takes out the dataaccumulated at the buffer RAM 334 based on directions of CPU 340 throughthe buffer manager 337, performs abnormal conditions of data, additionof the error correction code, etc. and generates the write-in signal tothe optical disk 315.

The laser control circuit 324 controls the output of the laser lightirradiated to the optical disk 315 based on directions of the write-insignal from the encoder 325, and the CPU 340.

The interface 338 is the bidirectional communication interface with thehost (for example, personal computer), and is based on the standardinterfaces, such as ATAPI (AT Attachment Packet Interface) and SCSI(Small Computer System Interface).

The program described in code decipherable by the CPU 340 is stored inthe ROM 339.

And the CPU 340 saves data required for control etc. temporarily at theRAM 341 while controlling operation of each part of the above accordingto the program stored in the ROM 339.

Next, the composition of the optical pickup device 323 etc. is explainedusing FIG. 53-FIG. 61.

The optical pickup device 323 is the spindle motor as shown in FIG. 53.

The pickup body 301 which receives the reflected light from the recordside while irradiating laser light to the record side of the opticaldisk 315 which is rotating by 322, the two seek rails 302 which guidemovement to the X-axis direction (space longitudinal direction) of thepickup body 301 while holding this pickup body 301, and the pickup body.

It is constituted including the seeking motor 301 (not shown) fordriving to the X-axis direction.

The pickup body 301 is stored in the center of housing 371 and thishousing 371, and includes the light-beam output system 312 which acts inthe direction perpendicular to the record side of the optical disk 315as the outgoing light beam whose wavelength is 660 nm, and the focusingsystem 311 which focuses the light beam from the light-beam outputsystem 312 in the predetermined position of the recording surface of theoptical disk 315.

The light-beam output system 312 is equipped with the light source unit351, the coupling lens 352, the beam splitter 354, the starting mirror356, the detection lens 358, the cylindrical lens 357, and thephotodetector 359, as shown in FIG. 54.

The light source unit 351 is equipped with the semiconductor laser (notshown) as a light source which emits light in the light beam whose wavelength is 660 nm. The light source unit 351 is fixed to the housing 371so that the direction with the maximum intensity of the outgoing lightbeam output from the light source unit accords with the direction of +X.

The coupling lens 352 is arranged at the +X side of the light sourceunit 351, and makes the outgoing beam abbreviation parallel light.

The beam splitter 354 is arranged at the +X side of the coupling lens352, and branches the reflected light (return light beam) from therecord side of the optical disk 315 in the direction of −Y.

The starting mirror 356 is arranged at the +X side of the beam splitter354, and changes the direction with the maximum intensity of theoutgoing beam through the beam splitter 354 into the direction of +Z.

The direction with the maximum intensity carries out incidence of theoutgoing beam changed into +Z direction to the focusing system 11through the opening of the housing 371 by the starting mirror 356.

The detection lens 358 is arranged at the −Y side of the beam splitter354, and condenses the return light beam which branched in the directionof −Y by the beam splitter 354.

The cylindrical lens 357 is arranged at the −Y side of the detectionlens 358, and operates orthopedically the return light beam condensedwith the detection lens 358.

The photodetector 359 is arranged at the −Y side of the cylindrical lens357, and receives the return light beam orthopedically operated by thecylindrical lens 357 in respect of the the received light.

The 4-division light-receiving component is used for the photodetector359, and the signal according to the amount of the received light isoutputted to the reproduction signal processing circuit 328 from eachlight-receiving component, respectively.

That is, while leading the light beam which acted as Idei from thesemiconductor laser to the focusing system 11, the optical path lengthfor leading the return light beam to the photodetector 359 is formed inthe center of housing 371.

FIG. 55 shows the focusing system in the optical pickup device of FIG.53. FIG. 56A shows the focusing system in the optical pickup device ofFIG. 53. FIG. 56B is a cross-sectional view of the focusing system takenalong the line A-A in FIG. 55A.

As shown, the focusing system 311 includes the objective lens 360, thelens holder 381 as a lens holding member, the first tracking coil 382 a,the second tracking coil 382 b, the first focusing coil 384 a 1, thesecond focusing coil 384 a 2, the third focusing coil 384 b 1, thefourth focusing coil 384 b 2, the base plate 385, the first yoke 386 a,the second yoke 386 b, the stem 387 as a stationary member, the firstradial tilt coil 388 a, the second radial tilt coil 388 b, the firstpermanent magnet 391 a, the second permanent magnet 391 b, the six linesprings (referred to as 392 a 1, 392 a 2, 392 a 3, 392 b 1, 392 b 2, and392 b 3) that have the conductivity as an elastic member, and the board393.

The base plate 385 is a rectangular plate-like member and the base plateis provided with the opening at the center portion thereof, which hasthe shape corresponding to that of the opening of the housing 371. Thelongitudinal direction of the base plate 385 corresponds to the Y-axisdirection, and the side surface of the base plate 385 is attached to thesurface of the housing 371 on the side of +Z direction so that theopening may lap with the opening of the housing 371. In addition, thebase plate 385 serves as a yoke for forming the magnetic circuit.

The first yoke 386 a and the second yoke 386 b are the plate-likemembers having the same configuration, and they have the predeterminedpositional relation and are fixed to the base plate 385.

The first yoke 386 a is arranged at +Y side edge section of the baseplate 385, and the second yoke 386 b is arranged at −Y side edge sectionof the base plate 385.

The stem 387 is the block-like member, and is attached to the surface onthe side of +Y of the first yoke.

The through holes extending in the Y-axis direction are formed in thisstem 387 at the three locations near the side edge of +X and at thethree locations near the side edge of −X, respectively.

The first permanent magnet 391 a and the second permanent magnet 391 bare the block-like permanent magnets having the same shape mostly.

The first permanent magnet 391 a is attached to the surface on the sideof −Y of the first yoke, and the second permanent magnet 391 b isattached to the surface on the side of +Y of the second yoke.

That is, the surface on the side of −Y of the first permanent magnet 391a and the surface on the side of +Y of the second permanent magnet 391 bconfront each other with respect to the Y-axis direction.

The surface on the side of −Y of first permanent magnet 391 a is dividedinto the four ranges, each having equal magnitude, by the magnetizationlimits CP1 of the X-axis direction and the magnetization limits CP2 ofthe Z-axis direction as shown in. FIG. 57A.

In the present embodiment, the range RC1 is indicated as the range whichis located on the +Z side of the magnetization limits CP1 and on the −Xside of the magnetization limits CP2. The range RC2 is indicated as therange which is located on the +Z side of the magnetization limits CP1and on the +X side of the magnetization limits CP2. The range RC3 isindicated as the range which is located on the −Z side of themagnetization limits CP1 and on the −X side of the magnetization limitsCP2. The range RC4 is indicated as the range which is located on the −Zside of the magnetization limits CP1 and on the +X side of themagnetization limits CP2. In addition, the adjacent ranges have thereversed polarity mutually.

The surface on the side of +Y of the second permanent magnet 391 b isdivided into the four ranges, each having the equal magnitude, by themagnetization limits DPI of the X-axis direction, and the magnetizationlimits DP2 of the Z-axis direction as shown in FIG. 57B.

In the present embodiment, the range RD1 is indicated as the range whichis located on the +Z side of the magnetization limits DP1 and on the −Xside of the magnetization limits DP2. The range RD2 is indicated as therange which is located on the +Z side of the magnetization limits DP1and on the +X side of the magnetization limits DP2. The range RD3 isindicated as the range which is located on the −Z side of themagnetization limits DP1 and on the −X side of the magnetization limitsDP2. The range RD4 is indicated as the range which is located on the −Zside of the magnetization limits DPI and on the +X side of themagnetization limits DP2. In addition, the adjacent ranges have thereversed polarity mutually.

Therefore, the range RC1 and the range RD1, the range RC2 and the rangeRD2, the range RC3 and the range RD3, and the range RC4 and the rangeRD4 confront each other, respectively. Moreover, the range RC1 and therange RD1, the range RC2 and the range RD2, the range RC3 and the rangeRD3, and the range RC4 and the range RD4 have the reversed polaritymutually, respectively.

Referring back to FIG. 55, the base board 393 is partially fixed to thesurface on the side of +Y of the stem 387 through a damping material,and provided with the plural input terminals and output terminals. Theplural signal lines of the motor driver 327 are connected to the inputterminals, respectively.

In addition, the base board 393 is provided to have some elasticdeformation in the Y-axis direction, in order to absorb vibrations ofthe Y-axis direction.

The lens holder 381 is provided to have a cube-like configuration, andit is arranged between the first permanent magnet 391 a and the secondpermanent magnet 391 b.

Moreover, as shown in FIG. 56B, the through hole extending in the Z-axisdirection used as the optical path length of the outgoing beam fromhousing 371 is formed in the center section of the lens holder 381.

In the edge on the side of +Z of the through hole, it is arranged sothat the optical axis and main shaft of the through hole of theobjective lens 360 may correspond mostly.

FIG. 58A through FIG. 58D show the respective coils for driving the lensholder 381 in the present embodiment.

The lens holder 381 includes the first tracking coil 382 a, the secondtracking coil 382 b, the first radial tilt coil 388 a, the firstfocusing coil 384 a 1, the second focusing coil 384 a 2, the thirdfocusing coil 384 b 1, the fourth focusing coil 384 b 2, and the secondradial tilt coil 388 b which are unified at the predetermined positionrelation respectively.

As the objective lens 360, the lens holder 381, and each coil are unitedand are moved together, and these components are unified and will becalled the movable portion.

The terminal (referred to as Ta3 and Tb3) for supplying: the drivecurrent to the terminal (referred to as Ta2 and Tb2) for supplying thedrive current to the terminal (referred to as Ta1 and Tb1) for supplyingthe drive current to each coil for radial tilts and each coil for thetrackings and each coil for the focuses is prepared in the lens holder381.

In the present embodiment, the terminals Ta1, Ta2, and Ta3 are formed inthe surface on the side of −X of the lens holder 381, and the terminalsTb1, Tb2, and Tb3 are formed in the surface on the side of +X of thelens holder 381.

And the end of the line spring 392 a 1 is connected to the terminal Ta1,the end of the line spring 392 a 2 is connected to the terminal Ta2, andthe end of the line spring 392 a 3 is connected to the terminal Ta3.

Moreover, the end of the line spring 392 b 1 is connected to theterminal Tb1, the end of the line spring 392 b 2 is connected to theterminal Tb2, and the end of the line spring 392 b 3 is connected to theterminal Tb3.

Each line spring is extending in the Y-axis direction, and those otheredges are connected to the output terminal of the board 393 by solderingetc. through the through hole prepared in the stem 387, respectively.That is, the movable portion is supported by the stem 387 in elasticitythrough the six line springs.

In addition, in the present embodiment, it is set up so that the supportcenter (referred to as S92) with each line spring may be mostly inagreement with the center of inertia (referred to as Sk) of movableportion.

The first coil 384 a 1 for the focuses, the second coil 384 a 2 for thefocuses, the third coil 384 b 1 for the focuses, and the fourth coil 384b 2 for the focuses are the coils of the same configuration mostlymutually. And it is connected by each coil for the focuses so that thesame drive current may be supplied.

The first coil 384 a 1 for the focuses and the second coil 384 a 2 forthe focuses are located in the +Y side of the lens holder 381,respectively as shown in FIG. 59A.

It is arranged at the position which counters almost equally to therange RC1 and the range RC3 of the first permanent magnet 391 a, and thecoil 384 a 1 and the coil 384 a 2 are arranged at the position whichcounters almost equally to the range RC2 and the range RC4 of the firstpermanent magnet 391 a.

The third coil 384 b 1 and the fourth coil 384 b 2 are located on the −Yside of the lens holder 381, respectively as shown in FIG. 59B.

It is arranged at the position which counters almost equally to therange RD1 and the range RD3 of the second permanent magnet 391 b, andthe coil 384 b 1 and the coil 384 b 2 are arranged at the position whichcounters almost equally to the range RD2 and the range RD4 of the secondpermanent magnet 391 b.

Thereby, when the drive current is supplied to the first focusing coil384 a 1, as shown in FIG. 60A, based on the current flowing through thecoil 384 a 1 and the magnetic flux from the range RC1 and the range RC3of the first permanent magnet 391 a, the force (first focal force: Ff1)occurs in +Z direction (or −Z direction).

When the drive current is supplied to the coil 384 a 2, based on thecurrent flowing through the coil 384 a 2 and the magnetic flux from therange RC2 and the range RC4 of the first permanent magnet 391 a, theforce (second focal force: Ff2) occurs in +Z direction (or −Zdirection), which is the same direction as the first focal force.

When the drive current is supplied to the third focusing coil 384 b 1,based on the current flowing through the coil 384 b 1 and the magneticflux from the range RD1 and range RD3 of the second permanent magnet 391b, as shown in FIG. 60B, the force (third focal force: Ff) occurs in +Zdirection (or −Z direction), which is the same direction as the firstfocal force.

When the drive current is supplied to the fourth focusing coil 384 b 2,based on the current flowing through the coil 384 b 2 and the magneticflux from the range RD2 and the range RD4 of the second permanent magnet391 b, the force (fourth focal force: Ff4) occurs in +Z direction (or −Zdirection), which is the same direction as the first focal force.

In the present embodiment, it is set up so that each focal force mayserve as the same magnitude mutually, the movable portion will be drivento +Z direction (or −Z direction) according to the magnitude of thedrive current.

In addition the driving direction can control each coil for the focusesbased on the flowing current.

Moreover, each coil for the focuses has the magnitude and theconfiguration according to the driving force needed.

The first tracking coil 382 a and the second tracking coil 382 b are thecoils of the same configuration mostly mutually.

The first tracking coil 382 a is on the +Y side of the lens holder 381,and arranged at the position which counters almost equally to the rangeRC1 and the range RC2 of the first permanent magnet 391 a, as shown inFIG. 59A.

The second tracking coil 382 a is on the −Y side of the lens holder 381,and arranged at the position which counters almost equally to the rangeRD1 and the range RD of the second permanent magnet 391 b, as shown inFIG. 59B.

In addition, a part of the first tracking coil 382 a overlaps a part ofthe first focusing coil 384 a 1 and a part of the second focusing coil384 a 2 about the Y-axis direction.

Similarly, a part of the second tracking coil 382 b overlaps a part ofthe first focusing coil 384 a 1 and a part of the second focusing coil384 a 2 about the Y-axis direction.

Moreover, it is connected so that the same drive current may be mutuallysupplied to the first tracking coil 382 a and the second tracking coil382 b.

Thereby, when the drive current is supplied to the first tracking coil382 a, as shown in FIG. 60C, based on the flowing current and themagnetic flux from the range RC1 and the range RC2 of the firstpermanent magnet 391 a, the force (first tracking force Ft1) occurs inthe direction of +X (or the direction of −X).

On the other hand, when the drive current is supplied to the secondtracking coil 382 b, as shown in FIG. 60D, based on the flowing currentand the magnetic flux from the range RD1 and the range RD2 of the secondpermanent magnet 391 b, the force (second tracking force: Ft2) occurs inthe direction of +X (or the direction of −X), which is the samedirection as the first tracking force.

In the present embodiment, it is set up so that the first tracking forceand the second tracking force may serve as the same magnitude mutually,and the movable portion will be driven in the direction of +X (or thedirection of −X) as a result according to the current value of the drivecurrent.

In addition, the driving direction (the direction of +X or the directionof −X) is controllable according to the current which flows in eachtracking coil.

Moreover, each tracking coil has the magnitude and the configurationaccording to the driving force needed.

In the present embodiment, it is set up so that the action center ofeach tracking force and the support center S92 (center of inertia Sk)with each line spring may be mostly in agreement, in tracking control athigh speed, the movable portion does not rotate in XZ plane.

The first radial tilt coil 388 a and the second radial tilt coil 388 bare the coils of the same configuration mostly mutually.

The first radial tilt coil 388 a is on the +Y side of the lens holder381, and is arranged at the position which counters almost equally tothe range RC3 and the range RC4 of the first permanent magnet 391 a, asshown in FIG. 59A.

The second radial tilt coil 388 b is on the −Y side of the lens holder381, and is arranged at the position which counters almost equally tothe range RD3 and the range RD4 of the second permanent magnet 391 b, asshown in FIG. 59B.

In addition, a part of the coil 388 a overlaps a part of the coil 384 a1 and a part of the coil 384 a 2 about the Y-axis direction.

Similarly, a part of the coil 388 b overlaps a part of the coil 384 a 1and a part of the coil 384 a 2 about the Y-axis direction.

Moreover, it is connected so that the same drive current may be mutuallysupplied to the coil 388 a and the coil 388 b.

Thereby, when the drive current is supplied to the first radial tiltcoil 388 a, based on the flowing current and the magnetic flux from therange RC3 and the range RC4 of the first permanent magnet 391 a, asshown in FIG. 60E, the force (radial tilt force: first Fr1) occurs in +Zdirection (or −Z direction).

As shown in FIG. 60F, when the drive current is supplied to the secondradial tilt coil 388 b, based on the flowing current and the magneticflux from the range RD3 and the range RD4 of the second permanent magnet391 b, the force (second radial tilt force: Fr2) occurs in +Z direction(or −Z direction), which is the same direction as the first radial tiltforce.

In addition, as shown in FIG. 61A and FIG. 61B, the point-of-applicationS88 a of the first radial tilt force and the point-of-application S88 bof the second radial tilt force are in the equal distance mostly fromthe support center S92 about the Z-axis direction, and the distance Lfsis set up so that the conditions represented by the following formula(1) may be satisfied.

In addition, Lns is the distance of the principal point St of theobjective lens 360 and the support center S92 about the Z-axisdirection, ktr is the spring modulus of the line spring, and krad is thetorsion-spring constant of the line spring.Lfs=krad/ktr/Lns  (1)

In the present embodiment, when the resultant of the first radial tiltforce and the second radial tilt force is set to Ftr, the amount Xtr ofmovement to the tracking direction of the movable portion is representedby the following formula (2).Xtr=Ftr/ktr  (2)

Moreover, the amount X of movement to the tracking direction of theprincipal-point position of the objective lens 360 when the movableportion rotates only the include angle theta 1 in XZ plane isgeometrically shown by the following formula (3).X=−Lns sin theta1=−Lns theta1  (3)

The angle of rotation theta 1 of the movable portion is represented bythe following formula (4).theta1=LfsFtr/krad  (4)

Then, when the relation of the formula (3) is used, the formula (3) canbe rewritten into the following formula (5).X=−LnsLfsFtr/krad  (5)

Furthermore, since it is set up so that the relation of the formula (1)may be satisfied, the formula (5) can be rewritten to the followingformula (6).X=−Ftr/ktr  (6)

Therefore, Xtr and X serve as the relation represented by the followingformula (7).Xtr+X=0  (7)

That is, in order for the movable portion itself to move in thedirection contrary to the move direction of the principal-point positionin the amount of the same movements even if the principal-point positionof the objective lens 360 moves by the rotation of the movable portionas shown in FIG. 61C, by the tilt control, the principal-point positionof the objective lens will not almost change as a result.

In addition, the angle of rotation of the movable portion can becontrolled by the magnitude of the current which flows in each coil forradial tilts, and the rotational polarity can be controlled by thepolarity of the current which flows in each coil for radial tilts.

Moreover, each coil for radial tilts has the magnitude and theconfiguration according to the driving force needed.

A description will be given of the operation of the optical pickupdevice 323.

The optical pickup device 323 is provided in the optical disk drive 320so that the Z-axis direction and the tangential direction of theperpendicular to the record side of the optical disk 315 direction ofthe track may correspond with the Y-axis direction.

That is, the X-axis direction turns into the tracking direction, and theZ-axis direction turns into the focusing direction.

After the light beam which acts in the direction of +X from the lightsource unit 351 serves as the parallel light with the coupling lens 352,which is incident to the beam splitter 354.

It is reflected in +Z direction by the starting mirror 356, and thelight beam from the beam splitter 354 is incident to the focusing system11 through the opening of the housing 371 and the opening of the baseplate 385.

The light beam incident to the focusing system 371 is inputted to theobjective lens 360 through the through hole of the lens holder 381, andit is focused onto the recording surface of the optical disk 315 as aminute light spot by the objective lens 360.

The reflected light from the recording surface of the optical disk 315is converted by the objective lens 360 into a return light beam which isthe parallel light again, and through the opening of the base plate 385and the opening of the housing 371 it is incident to the mirror 356.

The return light beam incident to the starting mirror 356 is reflectedin the direction of −X and it is incident to the beam splitter 354.

The return light beam which branches in the direction of −Y by the beamsplitter 354 is passed through the detection lens 358 and thecylindrical lens 357, and it is received by the photodetector 359.

Each light-receiving component which constitutes the photodetector 359outputs the current signal according to the amount of the received lightto the reproduction signal processing circuit 328, respectively.

Next, a description will be given of the control processing of theposition and attitude of the objective lens 360 in the optical diskdrive 320.

First, the focus control in the optical disk drive 320 will beexplained.

1. After the reproduction signal processing circuit 328 changes theoutput signal of the photodetector 359 into the voltage signal by thefirst I/V amplifier 328 a, it detects the focusing error signal by theservo signal detector 328 b, and outputs the detected signal to theservo controller 333.

2. The servo controller 333 generates the focal control signal forcorrecting the focal gap based on the focusing error signal, and outputsthe signal to the motor driver 327.

3. The motor driver 327 outputs the drive current for focal controlcorresponding to the focal control signal to the optical pickup device323.

4. In the optical pickup device 323, the drive current for the focalcontrol from the motor driver 327 is inputted into the predeterminedinput terminal of the board 393, and is supplied to each focusing coilthrough the line spring 392 a 3 and the line spring 392 b 3.

5. When the drive current flows through each focusing coil, the drivingforce according to the magnitude of the current and the polarity of thecurrent will occur, and the movable portion will be driven in thedirection of the focus control accordingly.

As a result, the objective lens 360 shifts in the direction of the focuscontrol, and the focal gap is corrected.

The tracking control in the optical disk drive 320 will now beexplained.

1. After the reproduction signal processing circuit 328 changes theoutput signal of the photodetector 359 into the voltage signal by thefirst I/V amplifier 328 a, it detects the tracking error signal by theservo signal detector 328 b, and outputs it to the servo controller 333.

2. The servo controller 333 generates the tracking control signal forcorrecting the track gap based on the tracking error signal, and outputsit to the motor driver 327.

3. The motor driver 327 outputs the drive current for tracking controlcorresponding to the tracking control signal to the optical pickupdevice 323.

4. In the optical pickup device 323, the drive current for the trackingcontrol from the motor driver 327 is inputted into the predeterminedinput terminal of the board 393, and is supplied to each tracking coilthrough the line spring 392 a 2 and the line spring 392 b 2.

5. When the drive current flows through each tracking coil, the drivingforce according to the magnitude of the current and the polarity of thecurrent will occur, and the movable portion will be driven in thetracking direction accordingly.

As a result, the objective lens 360 shifts to the tracking direction,and the track gap is corrected.

The tilt control in the optical disk drive 320 will now be explained.

1. After the reproduction signal processing circuit 328 changes theoutput signal of the tilt sensor 342 into the voltage signal by thesecond I/V amplifier 328 f, it detects the information about the mediatilt by the tilt detector 328 g, and outputs it to the servo controller333 as the tilt information signal.

2. The servo controller 333 generates the radial tilt compensationsignal for correcting the radial tilt based on the tilt informationsignal, and outputs it to the motor driver 327.

3. The motor driver 327 outputs the drive current for radial tiltcontrol corresponding to the radial tilt compensation signal to theoptical pickup device 323.

4. In the optical pickup device 323, the drive current for the radialtilt control from the motor driver 327 is inputted into thepredetermined input terminal of the board 393, and is supplied to theradial tilt coils through the line spring 392 a 1 and the line spring392 b 1.

5. When the drive current flows through each radial tilt coil, thedriving force according to the magnitude of the current and the polarityof the current will occur, and the movable portion will be inclined inXZ plane.

As a result, the objective lens 360 is rotated in XZ plane, and theradial tilt is corrected.

Next, the processing operation in the case of accessing the optical disk315 using the optical disk drive 320 will be explained.

First, the recording processing of the optical disk drive 320 will beexplained.

When the command of the record request is received from the host, theCPU 340 notifies the receipt of the command of the record request to thereproduction signal processing circuit 328 while outputting the controlsignal for controlling rotation of the spindle motor 322 based on thespecified record rate to the motor driver 327.

Moreover, the CPU 340 directs the accumulation to the buffer RAM 334 ofthe user data received from the host to the buffer manager 337.

When the rotation of the optical disk 315 reaches the predeterminedlinear velocity, the focal control, tracking control and tilt control(which will be generically called the position attitude control) will beperformed by the CPU 340.

In addition, the position attitude control is performed at any timeuntil the record processing is completed.

And the reproduction signal processing circuit 328 acquires ADIPinformation based on the output signal of the photodetector 359, andnotifies it to the CPU 340.

In addition, the reproduction signal processing circuit 328 acquiresADIP information for every predetermined timing until the recordprocessing is completed, and notifies it to the CPU 340.

The CPU 340 outputs the signal which controls the seeking motor to themotor driver 327 so that the optical pickup body 301 is located at thestart point where it performs writing to the optical disk based on ADIPinformation.

When the notice that the amount of user data accumulated at the bufferRAM 334 exceeds the predetermined value is received from the buffermanager 337, the CPU 340 directs generation of the signal for writing tothe encoder 325.

When the CPU 340 determines that the writing position of the opticalpickup body 301 is the start point based on ADIP information, it will benotified to the encoder 325.

Accordingly, the user data are recorded on the optical disk 315 throughthe encoder 325, the laser control circuit 324 and the optical pickupdevice 323.

The reproduction processing of the optical disk drive 320 will now beexplained.

When the command of the reproduction request is received from the host,the CPU 340 outputs to the motor driver 327 the control signal forcontrolling rotation of the spindle motor 322 based on the reproductionrate. At the same time, the CPU 340 notifies to the reproduction signalprocessing circuit 328 that the command of the reproduction request isreceived.

When the rotation of the optical disk 315 reaches the predeterminedlinear velocity, the position attitude control will be performed by theCPU 340.

In addition, the position attitude control is performed at any timeuntil the reproduction is completed.

And the reproduction signal processing circuit 328 acquires ADIPinformation based on the output signal of the photodetector 359, andnotifies it to the CPU 340.

In addition, the reproduction signal processing circuit 328 acquiresADIP information for every predetermined timing until the reproductionis completed, and it notifies it to the CPU 340.

The CPU 340 outputs the signal which controls the seeking motor to themotor driver 327 so that the optical pickup body 301 is located at thestart point for the reading on the optical disk based on ADIPinformation.

When the CPU 340 determines that the reading position of the opticalpickup body 301 is the start point on the optical disk based on ADIPinformation, it will notify it to the reproduction signal processingcircuit 328.

And after the reproduction signal processing circuit 328 detects the RFsignal based on the output signal of the photodetector 359 and performsrecovery processing, error-correction processing, etc., it isaccumulated to the buffer RAM 334 as reproduction data.

The buffer manager 337 transmits to the host through the interface 338,when the reproduction data accumulated at the buffer RAM 334 areassembled as sector data.

As is apparent from the above description, the tilt detection unit isconstituted by the tilt sensor 342 and the tilt detector 328 g in theoptical disk drive of the present embodiment.

Moreover, the processing mechanism is realized by the program performedby the CPU 340, the reproduction signal processing circuit 328, and theCPU 340.

According to the present embodiment, in the tilt control, the principalpoint of the objective lens does not need to be located near therotation axis of the movable portion, and the degree of freedom in thedesign of each coil increases, and it is possible to acquire therequired driving force easily. Therefore, it is possible to raise theservo control performance.

According to the present embodiment, it is possible to drive theobjective lens with sufficient accuracy at high speed.

Moreover, according to the optical pickup device of the presentembodiment, the rapid response and focal control of the objective lens,the tracking control, and the radial tilt control can be performedefficiently.

The optical spot of the predetermined configuration is stabilized withsufficient accuracy in the predetermined position of the optical disk,and is formed in it, and it is possible for the optical pickup device tooutput the signal, including the information, required for the positioncontrol of the objective lens, with sufficient accuracy.

Moreover, according to the optical disk drive of the present embodiment,it is possible for the optical pickup device to be stabilized withsufficient accuracy and to perform the high-speed access which includesreproduction, erasing and recording of the information storage medium.

In the foregoing embodiment, the case where the frequency of the drivesignal supplied to the tilt drive unit is comparatively low, or the casewhere the occurrence of cross action by tilt operation in the elasticrange in the displacement sensibility property of the optical pickupdevice is suppressed at a very low level is described.

When the frequency of the drive signal outputted to the optical pickupdevice is high, it is possible to set up such that the occurrence ofcross action by tilt operation may be suppressed at the very low levelin the inertia range in the displacement sensibility property of theoptical pickup device.

In this case, it will set up so that the conditions related to thedistance (referred to as Lfg) of the point of application of each radialtilt force and the center of inertia Sk of the movable portion about theZ-axis direction, which are indicated by the following formula (8), maybe satisfied.Lfg=Irad/m/Lng  (8)

In the above formula (8), Lng is the distance of the principal point Stof the objective lens 360 and the center of inertia Sk concerning theZ-axis direction, Irad is the moment of inertia of the movable portion,and m is the mass of the movable portion.

In addition, in the preferred embodiment, the support center S92 and thecenter of inertia Sk are mostly in agreement, or Lng=Lns. However, thepresent invention is not limited to this embodiment, and the supportcenter S92 may differ from the center of inertia Sk.

The reason will now be explained.

The acceleration alpha1 of movement to the tracking direction of themovable portion by each radial tilt force is shown by the followingformula (9).alpha1=Ftr/m  (9)

The amount X2 of movement to the tracking direction of theprincipal-point position of the objective lens 360 when the movableportion rotates only by the include angle theta 2 in XZ plane is shownby the following formula (10).X2=−Lng sin(theta2)=−Lng(theta2)  (10)

Then, the acceleration alpha2 to the tracking direction of theprincipal-point position is shown by the following formula (11).alpha2=−Lng(theta2″)  (11)

In the above formula (11), theta2″ is the angular acceleration of themovable portion.

The angular-acceleration theta2″ has the relation of the followingformula (12).theta2″=Lfg(Ftr/Irad)  (12)

Then, if the relation of the formula (12) is used, the above formula(11) can be rewritten to the following formula (13).alpha2=−Lng(Lfg(Ftr/Irad))  (13)

In the present embodiment, it is set up so that the relation of theabove formula (8) may be satisfied, and the above formula (13) can befurther rewritten to the following formula (14).alpha2=−Ftr/m  (14)

Therefore, alpha1 and alpha2 satisfy the relation represented by thefollowing formula (15).alpha1+alpha2=0  (15)

Namely, even if the principal-point position of the objective lens 360moves by the rotation of the movable portion, in order for the movableportion to move in the direction contrary to the move direction of theprincipal-point position with the same acceleration, the principal-pointposition of the objective lens by the tilt control will not almostchange as a result.

In addition, when the frequency band of the drive signal is wide, it ispossible to satisfy the conditions shown by the following formula (16).Irad/m=krad/ktr  (16)

That is, it is possible to make the primary resonance frequency in thetracking direction of the movable portion, and the primary resonancefrequency in rotation in XZ plane mostly in agreement.

In addition, when the above conditions cannot be satisfied by therestrictions on the design, or when there is a possibility of having thebad influence on the operation of the optical disk drive when the aboveconditions are satisfied, it is possible to adopt an intermediate valuebetween Lfg and Lfs.

Moreover, in the preferred embodiment, the case where the radial tiltcoils (first radial tilt coil 388 a and second radial tilt coil 388 b)are used as a pair of radial tilt coils is explained. However, thepresent invention is not limited to this embodiment.

As shown in FIG. 62A-FIG. 62D, it is possible to add the two pairs ofradial tilt coils (388 a 1, 388 a 2, 388 b 1, 388 b 2) as a coil forgenerating the couple moment.

The two pairs of radial tilt coils (388 a 1, 388 a 2, 388 b 1, 388 b 2)are the coils of the same configuration mostly with the focusing coils.

The laminating of the radial tilt coil 388 a 1 and the first focusingcoil 384 a 1 is mutually carried out to the Y-axis direction, and theyform the first laminating coil SC1.

The laminating of the radial tilt coil 388 a 2 and the second focusingcoil 384 a 2 is mutually carried out to the Y-axis direction, and theyform the second laminating coil SC2.

The laminating of the radial tilt coil 388 b 1 and the third focusingcoil 384 b 1 is mutually carried out to the Y-axis direction, and theyform the third laminating coil SC3.

The laminating of the radial tilt coil 388 b 2 and the fourth focusingcoil 384 b 2 is mutually carried out to the Y-axis direction, and theyform the fourth laminating coil SC4.

As shown in FIG. 63A, the first laminating coil SC1 is on the +Y side ofthe lens holder 381, and is arranged in the position which countersalmost equally to the range RC1 and the range RC3 of first permanentmagnet 391 a.

The second laminating coil SC2 is on the +Y side of the lens holder 381,and is arranged in the position which counters almost equally to therange RC2 and the range RC4 of first permanent magnet 391 a.

As shown in FIG. 63B, the third laminating coil SC3 is on the −Y side ofthe lens holder 381, and is arranged in the position which countersalmost equally to the range RD1 and the range RD3 of second permanentmagnet 391 b.

The fourth laminating coil SC4 is on the −Y side of the lens holder 381,and is arranged in the position which counters almost equally to therange RD2 and the range RD4 of second permanent magnet 391 b.

In addition, the focusing coils need a larger driving force than theradial tilt coils, and the focusing coils are arranged to the permanentmagnet side so that the strong magnetic flux against the focusing coilsmay occur.

Moreover, it is connected by each coil for radial tilts so that therespectively same drive current may be supplied.

Thereby, if the drive current is supplied to the coil 388 a 1 for radialtilts, as shown in FIG. 64A, based on the flowing current and themagnetic flux from the range RC1 and the range RC3 of the firstpermanent magnet 391 a, the force (third radial tilt force: Fr3) willoccur in −Z direction (or +Z direction).

If the drive current is supplied to the coil 388 a 2 for radial tilts,based on the flowing current and the magnetic flux from the range RC2and the range RC4 of the first permanent magnet 391 a, the force (fourthradial tilt force: Fr4) will occur in +Z direction (or −Z direction),which is opposite to the direction of the third radial tilt force.

If the drive current is supplied to the coil 388 b 1 for radial tilts,as shown in FIG. 64B, based on the flowing current and the magnetic fluxfrom the range RD1 and the range RD3 of the second permanent magnet 391b, the force (fifth radial tilt force: Fr5) will occur in −Z direction(or +Z direction), which is the same direction as the third radial tiltforce.

If the drive current is supplied to the coil 388 b 2 for radial tilts,based on the flowing current and the magnetic flux from the range RD2and the range RD4 of the second permanent magnet 391 b, the force (sixthradial tilt force: Fr6) will occur in +Z direction (or −Z direction),which is opposite to the direction of the third radial tilt force.

As the result, the couple moment (referred to as Mg) to rotate themovable portion in XZ plane will occur.

In this case, what is necessary is just to arrange each radial tilt coilso that the ratio of the couple moment Mg and the force Ftr may satisfythe following formula (17).Ftr/Mg=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (17)

The reason is explained below.

The amount X3 of movement to the tracking direction of theprincipal-point position of the objective lens 360 when the movableportion rotates only by the include angle theta3 in XZ plane isrepresented by the following formula (18).X3=−Lns(sin(theta3))=−Lns(theta3)  (18)

In this case, the angle of rotation theta3 in XZ plane of the movableportion is the addition value of the rotation by the couple moment Mgand the rotation by Ftr, as shown in the following formula (19).theta3=Mg/krad+Lfs(Ftr/krad)  (19)

Then, if the relation of the formula (19) used, the above formula (18)can be rewritten to the following formula (20).X3=−Lns(Mg/krad)−Lns(Lfs(Ftr/krad))  (20)

Furthermore, since it is set up so that the relation of the formula (17)may be satisfied, the above formula (20) can be rewritten to thefollowing formula (21). $\begin{matrix}\begin{matrix}{{X\quad 3} = {{{- {Ftr}}\left\{ {\left( {1/{ktr}} \right) - \left( {{Lns}\left( {{Lfs}/{krad}} \right)} \right)} \right\}} - {{Lns}\left( {{Lfs}\left( {{Ftr}/{krad}} \right)} \right)}}} \\{= {{- {Ftr}}/{ktr}}}\end{matrix} & (21)\end{matrix}$

Therefore, Xtr and X3 satisfy the relation represented by the followingformula (22).Xtr+X3=0  (22)

That is, even if the principal-point position of the objective lens 360moves by the rotation of the movable portion, in order for the movableportion to move in the direction contrary to the move direction of theprincipal-point position in the amount of the same movement, theprincipal-point position of the objective lens by the tilt drive willnot almost change as a result.

In addition, the direction of the rotation can be controlled by thepolarity of the flowing current of each radial tilt coil.

Moreover, each coil for radial tilts has the magnitude and theconfiguration according to the driving force needed.

In this case, what is necessary is just to arrange each coil for radialtilts so that the ratio of the couple moments Mg and Ftr may satisfy thefollowing formula (23) when the frequency of the drive signal is high.Ftr/Mg=Lng/{Irad(1/m−Lng(Lfg/Irad))}  (23)

The reason is explained below.

The acceleration alpha1 of movement to the tracking direction of themovable portion by the driving force Ftr is shown by the formula (9).

Moreover, the amount X4 of movement to the tracking direction of theprincipal-point position of the objective lens 360 when the movableportion rotates only by the include angle theta 4 in XZ plane is shownby the following formula (24).X4=−Lng(sin(theta4))=−Lng(theta4)  (24)

The acceleration alpha4 to the tracking direction of the principal-pointposition is shown by the following formula (25).alpha4=−Lng(theta4″)  (25)

In the above formula (25), theta4″ is the angular acceleration of themovable portion.

The angular-acceleration theta4″ is the addition value of the angularacceleration by the couple moment Mg and the angular acceleration by thedriving force Ftr, as shown in the following formula (26).theta4″=Mg/Irad+Lfg(Ftr/Irad)  (26)

Then, if the relation of the formula (26) is used, the above formula(25) can be rewritten to the following formula (27).alpha4=−Lng(Mg/Irad)−Lng(Lfg(Ftr/Irad))  (27)

Furthermore, since it is set up so that the relation of the formula (23)may be satisfied, the above formula (27) can be further rewritten to thefollowing formula (28). $\begin{matrix}\begin{matrix}{{{alpha}\quad 4} = {{- {{Ftr}\left( {{1/m} - {{Lng}\left( {{Lfg}/{Irad}} \right)}} \right)}} - {{Lng}\left( {{Lfg}\left( {{Ftr}/{Irad}} \right)} \right)}}} \\{= {{- {Ftr}}/m}}\end{matrix} & (28)\end{matrix}$

Therefore, alpha1 and alpha4 satisfy the relation represented by thefollowing formula (29).alpha1+alpha4=0  (29)

That is, even if the principal-point position of the objective lens 360moves by the rotation of the movable portion, in order for the movableportion to move in the direction contrary to the move direction of theprincipal-point position with the same acceleration, the principal-pointposition of the objective lens by the tilt control will not almostchange as a result.

In addition, in the case where the frequency band, of the drive signalis wide, at the time when the conditions are satisfied but there is apossibility of having the bad influence on the operation of the opticaldisk drive, or at the time when the conditions of the formula (23)cannot be satisfied by the restrictions on the design, what is necessaryis that Ftr/Mg satisfy the conditions represented by the followingformula (30).Lns/krad{(1/ktr)−Lns(Lfs/krad)}<Ftr/Mg<Lng/Irad{(1/m)−Lng(Lfg/Irad)}  (30)

Moreover, in the present embodiment, as shown in FIG. 65A-FIG. 65D, theradial tilt coil 388 may be provided around the perimeter of the lensholder 381′ in XY plane as a coil for generating the couple moment.

As shown in FIG. 66A, the radial tilt coil 388 is arranged on the −Yside of the lens holder 381 at the position which counters the range RC3and the range RC4 of the first permanent magnet 391 a. As shown in FIG.66B, it is arranged on the +Y side of the lens holder 381 at theposition which counters the range RD3 and the range RD4 of the secondpermanent magnet 391 b.

As shown in FIG. 67A, when the drive current is supplied to the radialtilt coil 388, the force (seventh radial tilt force: Fr7) occurs in −Zdirection (or +Z direction) based on the current flowing through theradial tilt coil 388 and the magnetic flux from the range RC3 of thefirst permanent magnet 391 a. At the same time, based on the samecurrent and the magnetic flux from the range RC3, the force (eighthradial tilt force: Fr8) occurs in +Z direction (or −Z direction), whichis opposite to the direction of the seventh radial tilt force.

Moreover, as shown in FIG. 67B, based on the current flowing through theradial tilt coil 388 and the magnetic flux from the range RD3 of thesecond permanent magnet 391 b, the force (ninth radial tilt force: Fr9)occurs in −Z direction (or +Z direction), which is the same direction asthe seventh radial tilt force. At the same time, based on the samecurrent and the magnetic flux from the range RD4, the force (tenthradial tilt force: Fr10) occurs in +Z direction (or −Z direction), whichis opposite to the direction of the ninth radial tilt force.

As the result, the couple moment (referred to as Mg2) to rotate themovable portion in XZ plane is generated.

In this case, what is necessary is just to arrange each radial tilt coilso that the ratio of the driving force Ftr to the couple moment Mg2 maysatisfy the following formula (31).Ftr/Mg2=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (31)

Moreover, in the present embodiment, the pair of the radial tilt coilsfor generating the couple moment with which each magnet range iscountered except the part extending in the Z-axis direction may bearranged additionally.

Moreover, in the present embodiment, the case where the surfaces of eachpermanent magnet which confront each other mutually are divided into thefour equal ranges, respectively. However; the present invention is notlimited to this embodiment.

For example, as shown in FIG. 68A and FIG. 68B, it is possible to divideeach surface into the two ranges by the magnetization limits (EP, FP) ofthe Z-axis direction.

That is, the third magnet 391 a′ is used instead of first permanentmagnet 391 a, and the fourth magnet 391 b′ may be used instead of beingthe second permanent magnet 391 b.

In the present embodiment, as shown in FIG. 68A, let the range RE1 andthe range on the side of +X be the ranges RE2 for the range on the sideof −X of the magnetization limits EP in third magnet 391 a′. Inaddition, the respective ranges have the reversed polarity mutually.

Moreover, as shown in FIG. 68B, let the range RF1 and the range on theside of +X be the ranges RF2 for the range on the side of −X of themagnetization limits FP in the fourth magnet 391 b′. In addition, therespective ranges have the reversed polarity mutually.

In this case, as shown in FIG. 69A-FIG. 69D, the radial tilt coil 388 a′is used instead of the first radial tilt coil 388 a, and the radial tilecoil 388 b′ is used instead of the second radial tilt coil 388 b.

As shown in FIG. 70A, the radial tilt coil 388 a′ is arranged, exceptfor the part extending in the X-axis direction, at the position toequally confront the range RE1 and the range RE2 of the third magnet 391a′.

As shown in FIG. 70B, the radial tilt coil 388 b′ is arranged in theposition to equally confront the range RF1 and the range RF2 of thefourth magnet 391 b′, except for the part extending in the X-axisdirection.

When the drive current is supplied to the radial tilt coil 388 a′, asshown in FIG. 71A, the force (11th radial tilt force Fr11, 12th radialtilt force: Fr12) of +X direction (or −X direction) occurs based on thecurrent flowing through the radial tilt coil 388 a′ and the magneticflux from the range RE1 and the range RE2 of the third permanent magnet391 a′. At the same time, the force (13th radial tilt force: Fr13) of +Zdirection (or −Z direction) and the force (14th radial tilt force: Fr14)of −Z direction (or +Z direction) occur.

As shown in FIG. 71B, when the drive current is supplied to the radialtilt coil 388 b′, the force (15th radial tilt force: Fr15, 16th radialtilt force: Fr16) occurs in the direction of +X (or the direction of −X)based on the current flowing through the radial tilt coil 388 b′ and themagnetic flux from the range RF1 and the range RF2 of the fourthpermanent magnet 391 b′. At the same time, the force (17th radial tiltforce: Fr17) of the +Z direction (or −Z direction) and the force (18thradial tilt force: Fr18) of the −Z direction (or +Z direction) occur.

In this case, what is necessary is just to arrange each radial tilt coilso that the ratio of the driving force Ftr2 of the X-axis direction byFr11, Fr12, Fr15 and Fr16 to the couple moment Mg3 by Fr13, Fr14, Fr17and Fr18 may satisfy the following formula (32).Ftr2/Mg3=Lns/krad{(1/ktr)−(Lns(Lfs/krad))}  (32)

In addition, when the frequency of the drive signal is high, and whenthe frequency band is wide, the approach that is the same as describedabove can be used.

Moreover, as shown in FIG. 72A and FIG. 72B, it is possible to use thepermanent magnets 395 a and 395 b with which the magnitude of each rangediffers mutually.

As the surface on the side of −Y of the permanent magnet 395 a is shownin FIG. 72A, it is divided into the two ranges by the magnetizationlimits GP of the Z-axis direction, and each range is further dividedinto the L-shaped range and the rectangular range.

In the present embodiment, the rectangular range on the side of −X ofthe magnetization limits GP is indicated by the range RG1, and theL-shaped range on the same side is indicated by the range RG2. Therectangular range on the side of +X of the magnetization limits GP isindicated by the range RG3, and the L-shaped range on the same side isindicated by the range RG4.

And the range RG1 and the range RG2 have the reversed polarity mutually,and the range RG3 and the range RG4 have the reversed polarity mutually.Moreover, the range RG1 is smaller than the range RG2, and the range RG3is smaller than the range RG4.

As shown in FIG. 72B, the surface on the side of +Y of the permanentmagnet 395 b is divided into the two ranges by the magnetization limitsHP of the Z-axis direction, and each range is further divided into theL-shaped range and the rectangular range.

In the present embodiment, the rectangular range on the side of −X ofthe magnetization limits HP is indicated by the range RH1, and theL-shaped range on the same side is indicated by the range RH2. Therectangular range on the side of +X of the magnetization limits HP isindicated by the range RH3, and the L-shaped range on the same side isindicated by the range RH4.

And the range RH1 and the range RH2 have the reversed polarity mutually,and the range RH3 and the range RH4 have the reversed polarity mutually.Moreover, the range RH1 is smaller than the range RH2, and the range RH3is smaller than the range RH4.

In this case, as shown in FIG. 73A, the first tracking coil 382 a isarranged at the position which equally counters the range RG2 and therange RG4 of the permanent magnet 395 a. As shown in FIG. 73B, thesecond tracking coil 382 b is arranged at the position which equallycounters the range RH2 and the range RH4 of the permanent magnet 395 b.

As shown in FIG. 73A, the first focusing coil 384 a 1 is arranged at theposition where the range RG1 and the range RG2 of the permanent magnet395 a counter equally to the part which adjoins the Z-axis direction,and the second focusing coil 384 a 2 is arranged at the position wherethe range RG3 and the range RG4 of the permanent magnet 395 a counteralmost equally to the part which adjoin the Z-axis direction.

Moreover, as shown in FIG. 73B, the third focusing coil 384 b 1 isarranged at the position where the range RH1 and the range RH2 of thepermanent magnet 395 b counter almost equally to the part which adjoinsthe Z-axis direction. The fourth focussing coil 384 b 2 is arranged atthe position where the range RH3 and the range RH4 of the permanentmagnet 395 b counter almost equally to the part which adjoins the Z-axisdirection.

As shown in FIG. 73A, the radial tilt coil 388 a 1 is arranged at theposition where about two thirds of this coil counters the range RG2 ofthe permanent magnet 395 a and the remainder of this coil counters therange RG1. The radial tilt coil 388 a 2 is arranged at the positionwhere about two thirds of this coil counters the range RG4 and theremainder of this coil counters the range RG2.

As shown in FIG. 73B, the radial tilt coil 388 b 1 is arranged at theposition where two thirds of this coil counters the range RH2 of thepermanent magnet 395 b and the remainder thereof counters the range RH1.The radial tilt coil 388 b 2 is arranged at the position where twothirds of this coil counters the range RH4 and the remainder thereofcounters the range RH3.

As shown in FIG. 74A and FIG. 74B, when the drive current is supplied toeach radial tilt coil, the driving force to move the movable portion tothe X-axis direction and the couple moment to rotate the movable portionin XZ plane occur.

Therefore, the movement of the principal-point position of the objectivelens generated by the radial tilt drive can be controlled by arrangingeach radial tilt coil so that the above-mentioned conditions related tothe ratio of the driving force and the couple moment may be satisfied.

Furthermore, as shown in, FIG. 75A and FIG. 75B, the permanent magnets396 a and 396 b having respective ranges with the shape of a trianglemay be used instead.

As shown in FIG. 75A, the surface on the side of −Y of the permanentmagnet 396 a is divided into the two ranges by the magnetization limitsIP of the Z-axis direction, and each range is further divided into thetwo triangle ranges.

In the present embodiment, the triangle range on the −X side of themagnetization limits IP which makes the magnetization limits IP one sideof the triangle range is indicated by the range RI2. The other trianglerange is indicated by the range RI1. The triangle range on the +X sideof the magnetization limits IP which makes the magnetization limits IPone side of the triangle range is indicated by the range RI4. The othertriangle range is indicated as the range RI3. In addition, the triangleranges which adjoin each other have the reversed polarity mutually.

As shown in FIG. 75B, the surface on the side of +Y of permanent magnet396 b is divided into the two ranges by the magnetization limits JP ofthe Z-axis direction, and each range is further divided into the twotriangle ranges.

In the present embodiment, the triangle range on the −X side of themagnetization limits JP which makes the magnetization limits JP one sideof the triangle range is indicated by the range RJ2. The other trianglerange is indicated by the range RJ1. The triangle range on the +X sideof the magnetization limits JP which makes the magnetization limits JPone side of the triangle range is indicated by the range RJ4. The othertriangle range is indicated as the range RJ3. In addition, the triangleranges which adjoin each other have the reversed polarity mutually.

In this case, as shown in FIG. 76A, the first tracking coil 382 a isarranged at the position which counters almost equally to the range RI2and the range RI4 of the permanent magnet 396 a. As shown in FIG. 76B,the second tracking coil 382 b is arranged at the position whichcounters almost equally to the range RJ2 and the range RJ4 of thepermanent magnet 396 b.

As shown in FIG. 76A, the first focusing coil 384 a 1 is arranged at theposition which counters almost equally to the range RI1 and the rangeRI2 of the permanent magnet 396 a. The second focusing coil 384 a 2 isarranged at the position which counters almost equally to the range RI3and the range RI4 of the permanent magnet 396 a.

Moreover, as shown in FIG. 76B, the third focusing coil 384 b 1 isarranged at the position which counters almost equally to the range RJ1and the range RJ2 of the permanent magnet 396 b, and the fourth focusingcoil 384 b 2 is arranged at the position which counters almost equallyto the range RJ3 and the range RJ4 of the permanent magnet 396 b.

As shown in FIG. 76A, the radial tilt coil 388 a 1 is arranged at theposition where about two thirds of this coil counter the range RI1 ofthe permanent magnet 396 a and the remainder thereof counters the rangeRI2. The radial tilt coil 388 a 2 is arranged at the position whereabout ⅔ of this coil counters the range RI3 and the remainder countersthe range RI4.

As shown in FIG. 76B, the radial tilt coil 388 b 1 is arranged at theposition where about two thirds of this coil counters the range RJ1 ofthe permanent magnet 396 b and the remainder counters the range RJ2. Theradial tilt coil 388 b 2 is arranged at the position where about twothirds of this coil counter the range RJ3 and the remainder counters therange RJ4.

As shown in FIG. 77A and FIG. 77B, when the drive current is supplied toeach radial tilt coil, the driving force to move the movable portion tothe X-axis direction and the couple moment to rotate the movable portionin XZ plane occur.

Therefore, the movement of the principal-point position of the objectivelens generated by the radial tilt drive can be controlled by arrangingeach radial tilt coil so that the above-mentioned conditions related tothe ratio of the driving force and the couple moment may be satisfied.

Moreover, in the present embodiment, the case where the tilt sensor isarranged apart from the optical pickup device is described. However, thepresent invention is not limited to this embodiment. It is possible thatthe tilt sensor be arranged within the optical pickup device.

It is possible to add the tilt detectors 328, and the circuit whichperforms the same processing to the optical pickup device. In theoptical pickup device of such embodiment, the signal with which theinfluence of the radial tilt is removed will be stably be outputted.

Moreover, as for the arrangement of the range in the permanent magnet;it is not limited to the above-described embodiment. It is adequate thatthe turning effort which rotates the movable portion around the rotationaxis of the Y-axis direction, and the translation force which offsetsthe movement of the principal point of the objective lens about theX-axis direction accompanying the rotation act on the movable portionalmost simultaneously with the tilt control.

Moreover, as for the composition and the arrangement position of theradial tilt coils, it is not limited to the above-described embodiment.It is adequate that the turning effort which rotates the movable portionaround the rotation axis of the Y-axis direction, and the translationforce which offsets the movement of the principal point of the objectivelens about the X-axis direction accompanying the rotation act on themovable portion almost simultaneously with the tilt control.

Moreover, in the above-described embodiment, the case where theinformation storage medium based on the specification of the DVD systemis used as the optical disk 315 is described. However, the presentinvention is not limited to this embodiment, and it is possible to usean information storage medium based on the specification of the CD(compact disc) system or a laser disk.

The present invention is applicable to any information storage medium towhich a light beam is focused in order to carry out at leastreproduction of information from the storage medium among the functionsof recording, reproduction and elimination.

As for the light source which outputs the light beam, not only the lightsource that outputs a light beam whose wavelength is 660 nm but also thelight source that outputs a light beam whose wavelength is 405 nm or thelight source that outputs a light beam whose wavelength is 780 nm may beused.

Moreover, in the above-described embodiment, the case where a singlelight sources is used is described. However, the present invention isnot limited to this embodiment, and it is possible to use a plurality oflight sources. In such a case, it is possible to use a multiplelight-source unit including any of the light source that outputs thelight beam whose wavelength is 405 nm, the light source that outputs thelight beam whose wavelength is 660 nm, and the light source that outputsthe light beam whose wavelength is 780 nm.

The present invention is not limited to the above-described embodiments,and variations and modifications may be made without departing from thescope of the present invention.

Further, the present invention is based on Japanese priorityapplications No. 2002-165616, filed on Jun. 6, 2002; No. 2002-198442,filed on Jul. 8, 2002; No. 2002-297166, filed on Oct. 10, 2002; and No.2002-334417, filed on Nov. 18, 2002, the entire contents of which arehereby incorporated by reference.

1-13. (canceled)
 14. An objective lens drive apparatus comprising: astationary member; a movable portion having an objective lens, anobjective-lens holding member holding the objective lens, and drivingcoils; and a plurality of rod-like elastic support members providedbetween the stationary member and the movable portion, each supportmember having an axial direction that is parallel to a third directionperpendicular to both a first direction and a second direction, thesupport members elastically supporting the movable portion to be movableto the stationary member, wherein the movable portion is supported bythe support members on both sides of the movable portion, and thesupport members are arranged on a single plane perpendicular to thefirst direction and in the third direction symmetrically with respect toan optical axis of the objective lens.
 15. The objective lens driveapparatus according to claim 14 wherein the driving coils comprise acoil generating a force in the first direction, a coil generating aforce in the second direction, a coil generating a force in a tangentialtilt direction, and a coil generating a force in a radial tiltdirection, and wherein the plurality of rod-like elastic support memberscomprise eight rod-like elastic support members of a conductivesubstance, and electric current is supplied to the respective coilsthrough said rod-like elastic support members.
 16. The objective lensdrive apparatus according to claim 14 wherein the single plane on whichthe support members are arranged is located near a principal point ofthe objective lens.
 17. The objective lens drive apparatus according toclaim 14 wherein a damping material is provided near portions of themovable portion to which the support members are attached.
 18. Theobjective lens drive apparatuses according to claim 14 wherein theplurality of rod-like elastic support members are formed by dividing asheet-like member which is integrally formed with the objective-lensholding member and the stationary member, into plural pieces.
 19. Theobjective lens drive apparatus according to claim 18 wherein theplurality of rod-like elastic support members which are formed bydividing the sheet-like member are partially bent to reduce rigidity inthe third direction.
 20. The objective lens drive apparatus according toclaim 14 wherein the plurality of rod-like elastic support members arearranged coaxially with respect to the third direction.
 21. Theobjective lens drive apparatus according to claim 14 wherein ends of thesupport members attached to the stationary member are fixed to elasticboards that are provided on the stationary member to be slightly movablein the third direction.
 22. The objective lens drive apparatus accordingto claim 14 wherein ends of the support members attached to the movableportion are soldered to lands of a printed circuit board, arranged atright angles to the first direction, on both sides of the movableportion in a radial direction thereof, and an effective length of eachsupport member is regulated by end surfaces of the printed circuit boardin the third direction.
 23. The objective lens drive apparatus accordingto claim 22 wherein the printed circuit board is arranged on an oppositeside of the objective lens with respect to a center of gravity of themovable portion.
 24. An objective lens drive apparatus comprising: astationary member; a movable portion having an objective lens, anobjective-lens holding member holding the objective lens, and drivingcoils; and a plurality of rod-like elastic support members providedbetween the stationary member and the movable portion, each supportmember having an axial direction that is parallel to a third directionperpendicular to both a first direction and a second direction, thesupport members being arranged in the first direction apart from eachother and elastically supporting the movable portion to be movable tothe stationary member at least in a tangential tilt direction, whereinthe movable portion is supported by the support members on both sides ofthe movable portion, and the support members are arranged in the thirddirection symmetrically with respect to an optical axis of the objectivelens, the end on the side of the stationary member which supported themovable portion by the support members from both sides in the thirddirection, and is estranged in the first direction in the supportmember, it is fixed to the part from which the radius of gyration on theelastic board which the width of face of the focusing direction isformed narrowly partially, respectively, and rotates the shaft of thetracking direction as a center differs, the objective lens driveapparatus is configured so that the elastic board is rotatablecorresponding to tangential tilt operation of the movable portion. 25.An objective lens drive apparatus comprising: a stationary member; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils; and a plurality ofrod-like elastic support members provided between the stationary memberand the movable portion, each support member having an axial directionthat is parallel to a third direction perpendicular to both a firstdirection and a second direction, the support members being arranged inthe first direction apart from each other and elastically supporting themovable portion to be movable to the stationary member at least in atangential tilt direction, wherein the movable portion is supported bythe support members on both sides of the movable portion, and thesupport members are arranged in the third direction symmetrically withrespect to an optical axis of the objective lens, the elastic boardbeing displaced to the third direction, and the support members beingfixed smaller than a distance of the ends on the side of the elasticboard a distance of the support member ends on the side of the movableportion in the focusing direction.
 26. The objective lens driveapparatus according to claim 24 wherein the objective lens driveapparatus is configured so that the distance in the focusing directionof the movable portion side ends of the support members is smaller thanthe distance in the focusing direction of the ends on the side of theelastic board.
 27. The objective lens drive apparatus according to claim24 wherein by arranging the twist shaft of the elastic board on theperpendicular flat surface almost as opposed to the optical axis of thepassage and the objective lens for the principal point of the objectivelens.
 28. The objective lens drive apparatus according to claim 26wherein the support members near an optical disk installation side arearranged to allot the axis of the member perpendicularly to the opticalaxis of the objective lens, and the elastic support of the side far fromthe optical disk installation side having made the axis of the memberincline to the optical disk.
 29. The objective lens drive apparatusaccording to claim 28 wherein the objective lens drive apparatus isconfigured to meet the conditions Ls1/Ls2=Lw1/Lw2 where Ls1 is adistance in the first direction of the twist shaft of the elastic boardand the support member ends on the stationary member on the optical diskinstallation side, Ls2 is a distance in the first direction of the twistshaft of the elastic board and the support member ends on the stationarymember on the opposite side of the optical disk installation side, Lw1is a distance in the first direction of the principal point of theobjective lens and the support member ends on the movable portion on theoptical disk installation side, and Lw2 is a distance in the firstdirection of the principal point of the objective lens and the supportmember ends on the movable portion on the opposite side of the opticaldisk installation side.
 30. The objective lens drive apparatus accordingto claim 25 wherein each of extended parts of the support members in theaxial direction is provided to have an offset in the tracking directionso as to avoid interference.
 31. The objective lens drive apparatusaccording to claim 24 wherein the plurality of rod-like elastic supportmembers are constituted by flat springs which are parallel to a planeperpendicular to the first direction.
 32. The objective lens driveapparatus according to claim 24 wherein the elastic board is constitutedby a flexible circuit board.
 33. The objective lens drive apparatusaccording to claim 24 wherein a viscoelasticity ingredient is providedbetween the elastic board and the stationary member.
 34. An opticalpickup device comprising: an objective lens drive apparatus; a laserlight source outputting a laser light beam to an optical disk; alight-receiving optical unit receiving a reflected light beam from theoptical disk; and an objective-lens control unit outputting a controlsignal to the objective lens drive apparatus based on the reflectedlight beam received by the light-receiving optical unit, the objectivelens drive apparatus comprising: a stationary member; a movable portionhaving an objective lens, an objective-lens holding member holding theobjective lens, and driving coils generating a first force in a firstdirection parallel to an optical axis of the objective lens and a secondforce in a second direction perpendicular to the optical axis of theobjective lens; and a plurality of rod-like elastic support members eachhaving an axial direction parallel to a third direction perpendicular toboth the first direction and the second direction, the support memberselastically supporting the movable portion so that the movable portionis movable to the stationary member in the first direction and thesecond direction, wherein the movable portion is supported by thesupport members on both sides of the movable portion in the thirddirection, the support members are arranged on different planesperpendicular to the first direction, and the movable portion isarranged to be movable in the third direction with the support members,so that the objective lens is rotatable around an axis of the seconddirection.
 35. An optical disk drive in which an optical pickup device,a rotation drive unit controlling rotation of an optical disk, and apickup drive unit moving the optical pickup device in a radial directionof the optical disk are provided, the optical pickup device comprising:an objective lens drive apparatus; a laser light source outputting alaser light beam to the optical disk; a light-receiving optical unitreceiving a reflected light beam from the optical disk; and anobjective-lens control unit outputting a control signal to the objectivelens drive apparatus based on the reflected light beam received by thelight-receiving optical unit, the objective lens drive apparatuscomprising: a stationary member; a movable portion having an objectivelens, an objective-lens holding member holding the objective lens, anddriving coils generating a first force in a first direction parallel toan optical axis of the objective lens and a second force in a seconddirection perpendicular to the optical axis of the objective lens; and aplurality of rod-like elastic support members each having an axialdirection parallel to a third direction perpendicular to both the firstdirection and the second direction, the support members elasticallysupporting the movable portion so that the movable portion is movable tothe stationary member in the first direction and the second direction,wherein the movable portion is supported by the support members on bothsides of the movable portion in the third direction, the support membersare arranged on different planes perpendicular to the first direction,and the movable portion is arranged to be movable in the third directionwith the support members, so that the objective lens is rotatable aroundan axis of the second direction.
 36. An objective lens drive apparatuscomprising: a stationary member having yokes; a movable portion havingan objective lens, an objective-lens holding member holding theobjective lens, and driving coils; a plurality of rod-like elasticsupport members each having an axial direction parallel to a tangentialdirection perpendicular to both a focusing direction and a trackingdirection, the support members being arranged on different planesperpendicular to the focusing direction, the support members being fixedto the movable portion at one ends thereof, fixed to the stationarymember at the other ends thereof and elastically supporting the movableportion so that the movable portion is movable to the stationary memberin the focusing direction and the tracking direction; and drivingmagnets attached to the yokes of the stationary member and arranged inthe vicinity of the driving coils to form magnetic circuits with thedriving coils, wherein the other ends of the support members of thedifferent planes fixed to the stationary member are arranged atdifferent locations that are apart from each other in the axialdirections thereof, thereby correcting a tangential tilt of theobjective lens.
 37. An objective lens drive apparatus comprising: astationary member fixed to a housing of an optical pickup device; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils; a plurality ofrod-like elastic support members each having an axial direction parallelto a third direction perpendicular to both a first direction and asecond direction, the support members having one ends connected to thestationary member and other ends connected to the objective-lens holdingmember, the support member elastically supporting the movable portion sothat the movable portion is movable to the stationary member in thefirst direction and the second direction; and a tilt driving unitsimultaneously generating both a rotating force to rotate the movableportion around a rotation axis in the first direction perpendicular toan optical axis of the objective lens, and a movement force to move themovable portion in the second direction parallel to the optical axis ofthe objective lens, based on at least one of a positional relationbetween a center of rotation of the movable portion and a principalpoint of the objective lens, a moment of inertia of the movable portionaround the rotation axis, and characteristics of the support members,the movement force serving to cancel a part of movement of the principalpoint of the objective lens caused by the rotation of the movableportion.
 38. An optical pickup device comprising: an objective lensdrive apparatus; a laser light source outputting a laser light beam toan optical disk; a light receiving optical unit receiving a reflectedlight beam from the optical disk; and an objective-lens control unitoutputting a control signal to the objective lens drive apparatus basedon the reflected light beam received by the light receiving opticalunit, the objective lens drive apparatus comprising: a stationary memberhaving yokes; a movable portion having an objective lens, anobjective-lens holding member holding the objective lens, and drivingcoils; a plurality of rod-like elastic support members each having anaxial direction parallel to a tangential direction perpendicular to botha focusing direction and a tracking direction, the support members beingarranged on different planes perpendicular to the focusing direction,the support members being fixed to the movable portion at one endsthereof, fixed to the stationary member at the other ends thereof andelastically supporting the movable portion so that the movable portionis movable to the stationary member in the focusing direction and thetracking direction; and driving magnets attached to the yokes of thestationary member and arranged in the vicinity of the driving coils toform magnetic circuits with the driving coils, wherein the other ends ofthe support members of the different planes fixed to the stationarymember are arranged at different locations that are apart from eachother in the axial directions thereof, thereby correcting a tangentialtilt of the objective lens.
 39. An optical pickup device comprising: anobjective lens drive apparatus; a laser light source outputting a laserlight beam to an optical disk; a light receiving optical unit receivinga reflected light beam from the optical disk; and an objective-lenscontrol unit outputting a control signal to the objective lens driveapparatus based on the reflected light beam received by the lightreceiving optical unit, the objective lens drive apparatus comprising: astationary member fixed to a housing of the optical pickup device; amovable portion having an objective lens, an objective-lens holdingmember holding the objective lens, and driving coils; a plurality ofrod-like elastic support members each having an axial direction parallelto a third direction perpendicular to both a first direction and asecond direction, the support members having one ends connected to thestationary member and other ends connected to the objective-lens holdingmember, the support member elastically supporting the movable portion sothat the movable portion is movable to the stationary member in thefirst direction and the second direction; and a tilt driving unitsimultaneously generating both a rotating force to rotate the movableportion around a rotation axis in the first direction perpendicular toan optical axis of the objective lens, and a movement force to move themovable portion in the second direction parallel to the optical axis ofthe objective lens, based on at least one of a positional relationbetween a center of rotation of the movable portion and a principalpoint of the objective lens, a moment of inertia of the movable portionaround the rotation axis, and characteristics of the support members,the movement force serving to cancel a part of movement of the principalpoint of the objective lens caused by the rotation of the movableportion.
 40. An optical disk drive in which an optical pickup device, arotation drive unit controlling rotation of an optical disk, and apickup drive unit moving the optical pickup device in a radial directionof the optical disk are provided, the optical pickup device comprising:an objective lens drive apparatus; a laser light source outputting alaser light beam to the optical disk; a light-receiving optical unitreceiving a reflected light beam from the optical disk; and anobjective-lens control unit outputting a control signal to the objectivelens drive apparatus based on the reflected light beam received by thelight-receiving optical unit, the objective lens drive apparatuscomprising: a stationary member having yokes; a movable portion havingan objective lens, an objective-lens holding member holding theobjective lens, and driving coils; a plurality of rod-like elasticsupport members each having an axial direction parallel to a tangentialdirection perpendicular to both a focusing direction and a trackingdirection, the support members being arranged on different planesperpendicular to the focusing direction, the support members being fixedto the movable portion at one ends thereof, fixed to the stationarymember at the other ends thereof and elastically supporting the movableportion so that the movable portion is movable to the stationary memberin the focusing direction and the tracking direction; and drivingmagnets attached to the yokes of the stationary member and arranged inthe vicinity of the driving coils to form magnetic circuits with thedriving coils, wherein the other ends of the support members of thedifferent planes fixed to the stationary member are arranged atdifferent locations that are apart from each other in the axialdirections thereof, thereby correcting a tangential tilt of theobjective lens.
 41. An optical disk drive in which an optical pickupdevice, a rotation drive unit controlling rotation of an optical disk,and a pickup drive unit moving the optical pickup device in a radialdirection of the optical disk are provided, the optical pickup devicecomprising: an objective lens drive apparatus; a laser light sourceoutputting a laser light beam to the optical disk; a light-receivingoptical unit receiving a reflected light beam from the optical disk; andan objective-lens control unit outputting a control signal to theobjective lens drive apparatus based on the reflected light beamreceived by the light-receiving optical unit, the objective lens driveapparatus comprising: a stationary member fixed to a housing of theoptical pickup device; a movable portion having an objective lens, anobjective-lens holding member holding the objective lens, and drivingcoils; a plurality of rod-like elastic support members each having anaxial direction parallel to a third direction perpendicular to both afirst direction and a second direction, the support members having oneends connected to the stationary member and other ends connected to theobjective-lens holding member, the support member elastically supportingthe movable portion so that the movable portion is movable to thestationary member in the first direction and the second direction; and atilt driving unit simultaneously generating both a rotating force torotate the movable portion around a rotation axis in the first directionperpendicular to an optical axis of the objective lens, and a movementforce to move the movable portion in the second direction parallel tothe optical axis of the objective lens, based on at least one of apositional relation between a center of rotation of the movable portionand a principal point of the objective lens, a moment of inertia of themovable portion around the rotation axis, and characteristics of thesupport members, the movement force serving to cancel a part of movementof the principal point of the objective lens caused by the rotation ofthe movable portion.